After six years serving as masters of Winthrop House, Stephen P. Rosen and Mandana Sassanfar announced plans to step down at the end of this academic year.

They informed the House community in an e-mail Wednesday, citing personal reasons for the decision.

Though Winthrop residents said the announcement didn't come unexpectedly—Rosen and Sassanfar have children, some of whom will soon be attending college—they said the Masters would be missed for their warmth and welcoming nature.

"To me, the most important thing about them: They're just kind, normal people that you want to be around," Caitlin v.V. Crump ’10 said.

In his e-mail, Rosen individually addressed sophomores, juniors, and seniors—a reflection of what Crump called Rosen and Sassanfar's emphasis on House community.

The Masters serve food in their residence to undergraduates every Sunday, and they've attempted to get to know as many sophomores as they can, she said.

"People in the House like them because they do more than manage the House—they try to know and become friends with the students," Stephen R. Barchick '09 said.

Rosen, the Beton Michael Kaneb Professor of National Security and Military Affairs, is perhaps more widely known for his career accomplishments, which span academia and government.

He has advised national military organizations—serving as the Director of Political-Military Affairs in the National Security Council and participating in the Gulf War Air Power Survey—and has written numerous award-winning books, including Winning the Next War: Innovation and the Modern Military.

Sassanfar, who is a professor of biology at MIT, has delved into science education throughout her career. She is the Director of High School Science Outreach at MIT, directs the Massachusetts Junior Academy of Science, and consulted with the Massachusetts Department of Education from 2000 to 2001.

But Rosen and Sassanfar aren't just fixtures in academic settings. They both sit in on House Committee meetings, which are run by undergraduates, and provide input, often about raising funds for HoCo projects.

Barchick, the outgoing HoCo secretary, said the House community will miss Rosen and Sassanfar's active participation in House life.

"I know they have a really difficult job, managing a lot of different things," he said. "But they've been doing a good job for the past six years, and people have been really pleased."

The Masters are also self-professed Strauss Cup aficionados. In fact, Rosen alluded to the intramural grand prize in his e-mail.

"[J]ust a warning: nobody graduates if we do not win the Strauss Cup (soon to be in the display case in the dining hall) again this year," he wrote.

According to Crump, who was commissioned by the Masters to spend last summer making artwork for Winthrop, Rosen and Sassanfar have made an effort to place art throughout the House, especially when it is Winthrop-centric.

Rosen and Sassanfar's departure announcement follows Pforzheimer House Masters Sue and James J. McCarthy's in November.

And other House Masters may soon follow suit. In an interview last month, Dean of the College Evelynn M. Hammonds said more might retire in the next few years. She also said she hopes to recruit minority members of the Faculty to fill vacated positions.

Neither Rosen nor Sassanfar could be reached for comment.

—Staff writer Ahmed N. Mabruk can be reached at amabruk@fas.harvard.edu.