Oswald (Pat) Monroe could tell from the way a child drew a picture of a house or a tree whether the youngster was being abused at home.

For 32 years Monroe worked as a psychologist in the D.C. public schools helping children who were sexually abused, mentally ill, drug addicts, slow learners or sometimes simply unloved. Even after he retired last year, he came back as a volunteer.

Last week more than 200 of Monroe's friends got together and gave him a belated retirement party complete with a sumptuous dinner of seafood and roast beef, and entertainment by a belly dancer and The Jimmy McPhail Combo.

"Mr. Monroe, out of 32 years of service to the D.C. public schools you have missed approximately two days," said Thomas Harper, an assistant superintendent, one of several who paid tribute to Monroe after dinner.

"I have worked in this school system for many years and I have not heard one person say a bad word about Pat Monroe," Harper continued.

"When Pat got done with children, many parents forgot that they had children who needed help," said Mary Young, former director of pupil personnel services for the public schools.

Monroe -- 71, with a warm smile, a friendly face and a big heart -- recalled in an interview after the dinner, "When I first started working for the public school system they didn't have psychologists. We were called research assistants back then . . . the school system had three." Now there are nearly 100 psychologists working in the public schools, he said.

He received most of his psychological training by taking graduate courses at Catholic, American, George Washington and McGill universities and at Trinity College.

"Most of my work has been with young children," he said. "By the time you get to high school you don't see as many problems because the students with problems are eliminated. They either drop out or they have some help."

Monroe discovered the students' problems by having them draw pictures. "I use what we call the person, tree, house technique," he said. "That's where you test a child by having him draw a person, then a tree and then a house . . . you can tell so much from what a child draws."

Monroe said 80 percent of the young boys, when they are asked to draw a human being, will draw a woman. "That's because they come from homes where the only parent is the mother; the female is their main role model," he explained.

Children are asked to draw a tree "because the tree represents the family, with the roots, the trunk and the limbs which represent the intellect," he said.

"I'd say 80 to 90 percent of the children I've asked to draw a tree, particularly the boys, will draw one with a hole in it. That means there are problems with the family," Monroe said.

The drawings also detect mental illness, he said.

"I asked this one little boy, he was only about six or seven years old , to draw a human being, and it was around Easter," Monroe recalled. "He drew a person with lots of blood, a tremendous amount of blood, and said, 'This is Christ and they're going to kill him' . . . that's an indication that the child is severely disturbed.

"I told the child's mother that he was either going to church too much or he needed help," Monroe said. The mother never took his advice, which he said is common. "So often I never know what happens to these children after I diagnose them."

Parents are very protective about their children, Monroe said. "They think 'you don't like my child' . . . they're defensive, you have to be very careful how you deal with the parents."

One 6-year-old boy that Monroe tested drew pictures with sexual themes. "I knew immediately he was being abused sexually . . . whenever there is a sexual theme in the very young children's drawings, it's a sign of sexual abuse." After talking to the family Monroe discovered an older brother was sexually abusing several family members.

" . . . With junior high school girls it's another story, some of the pictures they'd give me were sheer pornography, but you have to just say thank you and go on to the next test," he said. "You can never act shocked, they don't know the pictures are pornographic."

Monroe said that he still cannot detect which children are suicidal. "There are supposed to be indicators in our tests, but I think no one person can really know if a child is suicidal."

Monroe was born in December 1914. His mother died when he was 9 months old, so he grew up with his grandmother, father and brother in Le Droit Park, once the premiere address for the city's black middle class.

After graduating from Dunbar High School, he attended Howard University, joined the Army and later earned a master's degree from Columbia Teachers College in New York.

Although Monroe, who never married, officially retired at the end of 1984, he has continued to work for the past year as a volunteer school psychologist three days a week at Turner and Clark elementary schools in Southeast Washington.

"It's made retirement easier because I can set my own hours and I'm still doing what I love to do," he said. "I didn't want to retire, it was mandatory because of my age."

When will he retire completely? "Unless my health fails, I plan to keep on doing this for as long as I can."