It's Thanksgiving -- the time to gather together and ask all the family to come for roast turkey and pumpkin pie. But for millions of Americans, one question overshadows the festivities, a question that will dominate the holiday season: Where do the kids go? To Mom's? Or Dad's?

Stepfamily USA. Born most often out of the cauldrons of divorce, these reconstituted households are creating a whole new set of rules and rituals for American families.

Still, even the name -- stepfamily -- implies something different. Not quite a "real" family. Not the same as "normal" people.

Many stepfamily members are even reluctant to discuss their situation. First lady Nancy Reagan -- who is a stepdaughter, stepsister and stepmother -- declines to be interviewed or to make a statement about her experiences, saying (through her spokeswoman Elaine Crispen), "We just never thought of ourselves that way."

Yet divorce and remarriage are so common in the United States today that one in 10 children currently lives with a stepparent, and one in four will live in a stepfamily at some point before turning 18. Schools now publish directories cross-referenced to two sets of parents with different names. Engraved invitations to weddings and bar mitzvahs reflect a new etiquette -- one that acknowledges parents and stepparents. Graduations are often held in stadiums to allow several sets of parents, as well as other extended family, such as step-siblings and step-grandparents, to attend.

An estimated 4.5 million children live with their mother and a stepfather, according to Child Trends, a nonprofit research group. An additional 1 million live with a father and stepmother. "Neither of those figures counts the children who visit a home with a stepparent," says Dr. Nicholas Zill, executive director of Child Trends, which studies effects of social change on children.

Stepfamilies fit neither the perky image of television's "Brady Bunch" nor the dismal picture in fairy tales. Yes, there are sometimes wicked stepmothers who treat their stepdaughters like Cinderella, and yes, sometimes cruel stepfathers abuse their stepchildren or worse, the way Hansel's and Gretel's stepfather sold them to the witch for supper. But in general, growing research suggests that stepfamilies on the whole are not any worse -- or any better -- than "intact, nuclear" families.

"The idea that stepfamilies are necessarily pathological or that they will make their members pathological is a real myth," says Dr. James Bray, a clinical psychologist who studies stepfamilies at Texas Woman's University in Houston.

"I have cautious optimism for stepfamilies," adds Zill. "There's evidence so far that the majority of stepfamilies are able to adjust well."

What stepfamilies do suffer from, particularly in the early years, is stress -- the stress of having to integrate strangers into an instant "family." The knot that binds the newly married couple entangles children from previous marriages and often snags former spouses as well. Husbands and wives who divorced because they didn't get along find that they must share parenting decisions not just with an ex-spouse but with perhaps two other adults -- their new spouse and their former mate's new spouse.

"The family starts along a two-lane road, but then takes a detour called divorce, single parenting and then remarriage for some," says Betty Carter, a social worker who is director of the Family Institute of Westchester County in Mt. Vernon, New York. "They're now not on a two-lane road but on a six-lane superhighway. The family members continue along in a much more complex form."

In addition, children often feel ambivalence and guilt as they juggle the confusing emotions they feel toward their biological parent and stepparent.

"Children have the fantasy that their parents will get back together," says Patricia Papernow, a psychotherapist in Newtonville, Mass. "When you see children crying at the wedding of one of their parents, that's terrific. It means that children are doing the grieving that they should do. At that moment it is important to say to a child, 'Yes, I know you miss your mom. I know it's hard to take someone else in. No, you don't have to love them, but you do have to be civil. No one else is ever going to take the other parent's place.' "

How well a family adjusts to the complexity of being a stepfamily has a lot to do with how well a couple handled the divorce. "Divorce done properly prepares the family for remarriage," says Dr. Clifford Sager, director of family psychiatry at the Jewish Board of Family and Children Services in New York. "It's important for separating or divorced parents to maintain good contact with the children and not to denigrate one another."

The American ideal of Mom, Dad, two kids and a dog has never reflected the diversity of American life. "In the 19th century, close to a quarter of children saw one of their parents die before they reached 18 years of age," says Dr. Frank Furstenburg, a University of Pennsylvania sociologist who studies the family. So remarriage and stepparenting was a common occurrence.

Not until the 1940s and '50s "did we attain any kind of that ideal where almost all children had the experience of growing up with two parents through most of their childhood," Furstenburg said. Even in 1940, 28 percent of white children and 54 percent of black youngsters lived in something besides that "ideal."

By the 1960s, divorce began to overtake death as the reason families no longer stayed together. Today, almost half of children will not live with both of their parents. "We're talking about a substantial fraction of the population," says Furstenburg.

Yet stepfamilies often feel isolated, ashamed or embarrassed. They consider themselves not quite normal or even flawed.

"One of the most disastrous things for the stepfamily is to try and model themselves after a traditional nuclear family," says Dr. Constance Ahrons, associate director of the Marriage and Family Therapy Program at the University of Southern California.

Studies show that stepfamilies "are as good as other families in terms of their ability to adapt to problems and to change," says psychologist Bray. "They're just less connected {than intact families}. They can't be judged by the same criteria that intact nuclear families are judged by."

Children in stepfamilies do better economically on average than children in single-parent homes. They seem to have more behavior problems than children from nondivorced families, but about the same as those from single-parent families.

"The reality is that there are a lot of positive benefits for stepfamilies," says Thomas Seibt, a former Catholic priest and now a marriage and family therapist at the California Family Study Center in Los Angeles. "I think kids can come out of a stepfamily with the opportunity for a lot better model of what a happy and good family can be like," adds Seibt, who is the father of five stepchildren and two biological youngsters. In the Trenches

"I don't know what's the matter here," a 25-year-old stepmother said three months after she had married a man with four children. "You'd think by now things would be better. I feel like I have failed. And my husband is wondering what's wrong, too." ::

No one says that the road for stepfamilies is easy. But many underestimate the time needed to confront the challenges they face. In a stepfamily, virtual strangers find themselves suddenly sharing quarters because two adults decided to get married. The passage from newly married stepfamily to well-functioning stepfamily takes time -- by most accounts a minimum of four years, and sometimes as long as nine years.

Psychotherapist Papernow, who is herself a stepparent, believes that there are three major stages to "familydom," as she puts it. In the beginning stages, the family remains much as it was before the remarriage. The primary relationship is between each biological parent and his or her children. "The stepparent is an outsider to the system," Papernow says. This is a difficult time, she says, because studies show that families function best when the couple acts as the central team, rather than one parent and the children.

The new couple not only jumps into marriage without much of a honeymoon period, but also must confront the immediate task of parenting before they really know each other -- something that couples without children don't have to do.

Couples in a stepfamily "are faced with the painful experience of feeling fundamentally different about the children," Papernow says. "The biological parent feels pulled, engaged, worried and eager to please, while the stepparent often feels rejected, ignored and competitive with the same child."

To be successful, the stepfamily must move through the stages from this biologically based minifamily to a unit with a strong, cooperative couple at the helm.

During this transition stepparents will move through several phases. In the first months, people begin with fantasies ("I'm so glad to have a new mother/father for my kids" and "I love my new partner so of course I will love his/her kids"), move to what Papernow calls immersion (where fantasy hits reality) and then reach a state of awareness (first with the feeling that "something is wrong here and it's my fault," then to "something's wrong here and I don't like it").

The family then enters a middle stage of adjustment, during which it begins to unfreeze and shift. This stage starts with mobilization (where the stepparent rocks the boat rather than jumping ship) and ends with action (where both partners see themselves on the same side, trying to figure out how to resolve a complex set of stepfamily needs and problems).

By the final stage of adjustment, stepfamily members know each other well. New rules and rituals are set, whether it means the hours television is allowed or the weekly Sunday night dinner when the children return from visiting their other parent. In this last phase, the family "solidifies with reliable, nourishing step-relationships, particularly between the couple," Papernow says.

Some families make it through the entire adjustment cycle "in about four years," she says. "Average families take about seven years." Other families never make it. They get "stuck" in the early stages and often see divorce as the only option.

Keys to Success

How successful a family is in making the transition depends on the couple, the ages and the sexes of the children, the relationship with past spouses and whether or not they choose to have children of their own.

Younger children and older adolescents are most readily integrated into a new marriage. "It's easiest to be a stepparent to children before they reach age 3," says family therapist Seibt. That's a time "when they haven't had an opportunity to get to know their biological parent that well." The stepparent can literally "step in" and be accepted and loved.

The most difficult time to be a stepparent is when the children are ages 9 to 15. Studies by Mavis Hetherington at the University of Virginia show that "that's a terrible time for parents to get remarried," Hetherington says.

One reason is that children who have lived in a single-parent household "grow up faster," Hetherington says. "They have more power, more independence and more responsibility than children in two-parent families."

As a result, these youngsters often resent the addition of the stepparent, who takes away some of their responsibilities and relegates them back to the role of child.

To complicate matters, 9- to 15-year-olds are approaching or going through puberty. "It's the awakening of sexuality," Hetherington says. "It's a hard time for intact families -- and even more difficult for stepfamilies."

New studies suggest that daughters may have a harder time adjusting to stepfamily life than sons. It seems that the happier and more satisfied the remarried couple is with each other, the "more ticked off the daughters are, the more they feel irritable, resistant and angry," says Hetherington. "They're feeling left out."

"It's probably because girls focus more on the home and on the parent relationship than boys do."

Boys, on the other hand, often have more conflict with single mothers. The addition of a stepfather is a welcome relief; it provides a buffer between them and their mothers.

'Be Patient'

Eleven years ago, when actress Marlo Thomas married Phil Donahue, the talk show host, she became the stepmother to five children. Four of them -- all boys -- lived with Donahue. The youngest child, a girl named Mary Rose, lived with her mother.

"I went into this totally foolhardy," says Thomas, who is the author of "Free to Be . . . a Family." "I thought I was marrying a man that I love and, by the way, he had these kids. For some reason, my wisdom failed me. They were these little boys and they seemed so cool. I really wasn't seeing them as little children who needed a lot of attention."

Thomas had never been married before, nor had she ever been seriously involved with a man who was a father. "I just hadn't been around children," she says now. "I wasn't ready for it at all. I went into it with my eyes closed a bit."

"Patience is a good thing to think of," Thomas says. "Don't have high expectations. Don't expect that you and they will fall in love right away. Be patient with the differences and patient with your inability and others' inability to blend right off. It isn't going to happen right away. But it is kind of magical how you are all of a sudden like family."

For Thomas, the turning point came when one of her stepsons was injured in a serious car accident. "When that happened, I realized how much a part of the family I was and needed to be. By that time, I had been sort of a fairy stepmother, bringing good will, like Auntie Mame . . . But the whole thing hit me as to how much everybody needed me and how much I could contribute."

"I even understood my attachment to their {the boys'} mother . . . These are her children, but these are my children too. I have a special place, a place that no one else can fill. That's very rewarding." ::

Stepparents can find their equilibrium in their new family by moving slowly. "Being consistent in discipline helps," says the University of Virginia's Hetherington. "Being supportive but firm and not trying to move in too fast; not trying to make the child feel displaced. Making sure that the child gets a lot of attention and affection. Time itself is very important."

So is finding special moments for the couple to be alone. Putting the couple first is crucial to the family's survival -- although it may not ease the strain in stepparent/stepchildren relationships at first.

"It looks like people can have very good relationships with their spouses and terrible relationships with their stepchildren," says University of Texas's Bray. "That's something you don't see in nondivorced families." ::

"Stepchildren feel like there is a card game and they have been dealt out," says syndicated columnist Erma Bombeck, who became a stepdaughter at age 11, two years after the death of her father, when her mother remarried. As a stepchild, "you feel like you have nothing to play, no choice, no say in anything . . . "I was angry. My mother did all the right things to prepare me. But I felt like the person who goes to a Broadway play expecting to see someone famous and finds out that an understudy will be taking the role. I wanted my real father or no father at all."

Young Erma and her stepfather both tried to enlist the support of Erma's mother. "But she remained like Miss Switzerland, and then we both felt cheated," Bombeck says today. "She sort of let us hammer it out by ourselves. I know that must have been difficult for her."

The "hammering out" was done with silent standoffs. "We never fought," says Bombeck. "We just didn't say anything. It was the quietest house."

It took about "five to 10 years before we really began to feel really comfortable with each other," Bombeck says. "It has worked out so well at this point. I cannot remember what my natural father looked like. It's this man who raised me who is so important."

As a high school senior, Bombeck desperately wanted a class ring. "But my mother said no. At the final moment, the ring appeared. I said, 'Thank you so much,' to my mother. But she said, 'I didn't buy it for you, your father bought it.' I thought to myself, 'Why did he do this? I loved him for it, and I half resented him.' "

Mixed Emotions

Stepchildren feel torn. They are pulled between their feelings for their biological parents and their feelings for this new, "instant" parent who has suddenly entered their lives.

"There isn't a stepchild worth his salt who doesn't have some loyalty conflicts," says Dr. Judith S. Wallerstein, executive director of the Center for the Family in Transition in Corte Madera, Calif. Children need to have permission from their biological parents to get to know -- and hopefully feel close to -- a stepparent. "They need to be reassured that the appropriate parent won't feel betrayed," Wallerstein says.

A noncustodial parent who is alcoholic or otherwise viewed as "inadequate" may only intensify a child's fear of betrayal. "Children often feel protective of and responsible for a so-called 'weak' parent," says Papernow.

Unless these issues are resolved, they can strain the new marriage -- sometimes to the breaking point. Often families bail out early if the stepfamily situation doesn't seem to be working. "Stepfamilies sometimes see only the trees and not the forest," says marriage and family therapist Seibt. "They can see only the here-and-now pain and the panic. Parents say, 'I stayed in my last marriage for 15 years, I'll never do that again to my kids,' and they bail out early . . . They think, 'I'm not going to go through this again.' "

What distinguishes the families who make it through the adjustment stages more quickly is a commitment to understanding one another's feelings.

"Regular families have a lot of problems too," says Jeff Robbins of Silver Spring, who has a 16-year-old daughter from a previous marriage and is the father of two young sons from his second marriage. "Some of the problems of stepfamilies are problems of normal human existence."

"When I get mad at my wife, I have to stop and think, 'Could I have handled it as well if it had been my wife who had had the child, and I were the one thrown into an instant family?' "

Having a mutual child also seems to help some stepfamilies reach a new level of adjustment. "The new baby is the one person in the family to whom everyone is biologically related," says Dr. Katherine Baker, a social worker with a private practice in the District, who chairs the professional committee of the Stepfamily Association of America.

"The arrival of the new baby makes a statement both to the outside world and to the inside world of the remarried family about the family's commitment to a future as a stable childrearing unit." ::

"I was a little confused when my mother got married to my stepfather," says Rachael Simmons, a 10-year-old who lives in Columbia, Md., with her mother, her stepfather Allan Misch, and her 2 1/2-year-old half sister, Melissa. "

"At first, I was a little disappointed because my father wasn't going to live with me anymore, but I found out later on that I would get to see him and that it wouldn't be that bad."

Then last July, when Rachael's father remarried, she got two stepsisters -- ages 8 and 10. Rachael acted like a veteran. "I sort of told them that it was nothing to worry about. I managed to get through it, so I imagine that they will, too."

Being part of a stepfamily is "not as scary like you would think it is," says Rachael. "It's nice to have a stepmother and a stepfather and stepsisters and brothers. It's an experience that you can tell other people about. It will make you special."

STEP-. Step comes from the old English and Middle English steop, which is in turn derived from astepan (to bereave) and from bestepan (to deprive of children), according to the Random House dictionary. A stepparent is the new spouse of someone's mother or father. FAMILYDOM. The goal of a stepfamily, after it overcomes a period of adjustment. Term is used by some psychotherapists. BLENDED FAMILY. A stepfamily in which each adult has brought children to the marriage. Also known as a complex stepfamily. MUTUAL CHILD. The biological child of a couple who have children from previous marriages. SIMPLE STEPFATHER/STEPMOTHER. Someone who marries a new spouse with children but has no children of his or her own. BINUCLEAR FAMILY. A situation in which two separate households -- mother's and father's -- form one family system for a child.