GAIL R. RUSCETTA changed careers for the first time when she had children. A theater major who bounced between acting gigs in her 20s, Ms. Ruscetta took the kind of leap that overachieving city dwellers often fantasize about: She and her then husband moved to Montana and opened a horse farm and riding school.

Fifteen years later, Ms. Ruscetta — who was an active volunteer in her children’s classrooms and then helped home-school them — was going through a divorce. Time for another career switch.

This time, she decided to try teaching. Ms. Ruscetta, 57, moved to Virginia and enrolled in a yearlong, $3,500 training course designed by the state Education Department for career changers. She financed her training and living expenses from the sale of a dressage horse, and in the fall of 2012 she started a job at a public middle school in Alexandria, teaching English as a second language.

She figures this career will stick. “I’ll probably be working until I’m 85,” she said.

Teaching, with the draw of doing good, the steady (if unspectacular) paychecks, summers off and solid pension benefits, has long been perceived as a durable second — or third — career.