To become a teacher, Mary Ann Richardson left a $113,000-a-year job lobbying Congress as a U.S. deputy assistant secretary in the Labor Department.

Now she's a 46-year-old intern at Falls Church High School, a substitute teacher in history, government and civics without her own classroom or even her own desk. Next year, after she receives her master's degree in education, she will be applying for teaching jobs that pay about $80,000 a year less than what she used to earn.

She grapples with a new identity and the loss of family income that she worked 16 years to get and will never see again. But, she said, "when those kids look up to you or they're having a crisis and you can help . . . I can tell you right now, I have found a purpose."

The teaching profession, shunned for decades by college graduates in search of higher pay and prestige, is attracting a growing number of people who started their careers in another field. Some are downsized corporate executives who've heard about the national teacher shortage and are enticed by the job security. Others, like Richardson, are disenchanted lawyers and lobbyists who found that their high salaries did not make up for job pressures.

They are being lured, too, by an easing of teacher licensing requirements for career-switchers in many states and school districts, a trend that is likely to continue as the national teacher shortage worsens.

About 55 percent of the students currently enrolled in post-undergraduate teaching programs started their careers in another field, according to a study to be released this week by the National Center for Education Information, a Washington-based think tank. The study also found that 27 percent of universities have programs solely for second-career teachers, up from 3 percent in 1984.

Officials in several Washington area school districts said they are seeing more people like Richardson, although they do not keep such figures.

"People used to be driven by the financial rewards of their career," said Kevin North, the director of employment for Fairfax County schools. "People are starting to step back and say, `Other things are more important to me, and I want something more fulfilling.' "

Second-career teachers are appealing job candidates in several respects, said Linda Darling-Hammond, a professor of education at Stanford University and director of the National Commission on Teaching & America's Future. They are more mature than first-career teachers and often have experience with children through parenting. And because their decision to teach usually requires a substantial pay cut, they tend to have a deeper commitment to public education, she said.

Jerome "Rick" Peck, 55, a first-year science teacher at Loudoun County's Seneca Ridge Middle School, said the biggest attribute he brings to the classroom is "the ability to say to the kids -- and to mean it and to know it -- `Hey, this is something you're going to need later in life.' "

A certified public accountant with a master's degree in business administration from the Wharton School, Peck was earning a six-figure salary as chief financial officer of a magazine publishing company until it was sold a few years ago. He was financially secure and his decision to teach was "really selfish," Peck insists, because he saw it as something he would enjoy.

Five weeks into the school year, he still feels that way. But the transition hasn't been easy. He is mired in more paperwork than he expected. Many of his students fared poorly on the first test he gave, about the metric system, and some complained that he was lecturing too fast.

"When it comes to teaching, I'm definitely still learning," Peck said.

James R. Fields, 38, a former supervisor at United Parcel Service, is studying for his master's degree in education at George Washington University and substitute teaching at Sligo Middle School in Silver Spring.

Fields was earning $59,000 a year after 14 years at UPS. But when he moved from the Miami area to Montgomery County to get married, the company wouldn't transfer him.

He probably won't earn more than $35,000 a year when he gets a full-time teaching job next year. Fields said he is lucky that his wife, a gynecologist, has a salary that allows him to pursue teaching.

Fields, who is African American, said he hopes to be a strong influence on young black males. But right now, his main goal is to learn the routines of running a classroom. He said it's a challenge sometimes just to get his students to settle down -- never mind actually paying attention and comprehending his lessons.

"It's kind of tough as a sub -- [the students] think it's a field day," Fields said. "In a sense I see that as a plus; you quickly develop some classroom management skills."

Tom Brannan, 52, quit his $83,000-a-year job as an assistant city manager in Alexandria to enroll in the master's degree program at George Washington. He enjoyed many aspects of his job but not the long hours and frenetic pace. Time with his family was often cut short, he said.

In just a few weeks as a substitute teacher at Fairfax's George Marshall High School, Brannan already has seen rewards. One day, he was assigned on short notice to teach a history class, with little time to prepare a lesson. After sweating out the period, the bell rang and the students filed out. One stopped to ask him: "Are you gonna be back any time soon?"

Career-switchers typically take fewer education courses than students who go into teaching as a first career but often get more field work in schools.

Despite the growing calls from politicians and school officials to streamline the certification process for second-career teachers, they still may face challenges getting hired, said C. Emily Feistritzer, president of the National Center for Education Information.

Some may possess several advanced degrees, which would put them at a higher pay scale than most beginning teachers. Feistritzer said she has spotted another hurdle: Principals are sometimes less inclined to put older adults on their teaching staff because they won't be as easy to supervise as a 22-year-old college graduate.

Amy Harris is 26, younger than many of the other teachers who started in a different profession. She gave up a job at a brokerage firm in Minneapolis to lead 27 fifth-graders at Loudoun's Cool Spring Elementary School. Although she didn't take much of a pay cut to become a teacher, she eventually would have earned far more if she'd stayed in financial services.

She acknowledges that she second-guesses her decision once a month, when she writes a check to pay down $25,000 in debt from graduate school loans. But she is energized by her students. "I really enjoy their wit and their cleverness," she said.

Richardson's journey toward teaching began last year, when her mother was dying. She came to live with Richardson for the last four months of her life, during which mother and daughter had many soul-searching talks about careers, family and, above all, happiness.

"She said, `Look, you've got about 20 years [of working] left -- you need to do what you think is important and what you want to do,' " Richardson recalled.

Richardson, whose husband is an archivist, has put her two children on strict allowances to reduce household expenses since she quit her high-paying Labor Department job.

The worst of it, she said, is being viewed as an inexperienced newcomer at age 46.

"I worry that when I get done with this program, I have to start over and sell myself again," she said. "If I get through this, they should want me!"