There was a day when Kaneb Professor of National Security and Military Affairs Stephen P. Rosen ’74 couldn’t hold down a job as a teaching fellow (TF).

“I was arrogant; I was opinionated; I was a world-class bad teacher,” he recalls.

But today the renowned military scholar is recognized by students and colleagues as one of the College’s top teachers.

And next year, the man who was once a bad TF but now consistently receives top marks in the CUE Guide, will take over as Master of Winthrop House.

Rosen, who was born and raised in New York, was a risk-taker during his student days, trying out hiking and skydiving and starting his government senior thesis just two months before it was due.

The daredevil scholar has bad memories of his first teaching experience, as a TF for Harvard’s government department, where he attended graduate school.

“I had to grow up a lot before I could become a good teacher. It took a while, but I did,” he says.

Then-head tutor Nancy Rosenblum, now Clark professor of ethics in politics and government, told him “it was not a good idea” to continue teaching, Rosen recollects. Rosenblum says she does not remember Rosen’s teaching situation.

After finishing his dissertation in 1979, Rosen became the director of political-military affairs for the National Security Council and a consultant for President Reagan’s commission on long-term military strategy.

“The world did not need another bad teacher,” Rosen says, recalling his decision to leave academia.

After leaving his post at the National Security Council, Rosen took up a research position at the Naval War College from 1986-1990.

During his last year there, however, he returned to the head of the classroom.

“I taught guys who were 10 years older than me and had been the heads of aircraft carriers....They were skeptical about a civilian kid teaching them,” he says, emphasizing that the challenge helped him learn to teach well.

Rosen returned to Harvard in 1990, and since returning to his alma mater, he says teaching has become one of his favorite parts of academic life.

“It’s almost like being a performer,” he says. “You get feedback every day you teach. You leave class thinking ‘Today my act worked.’”