Harvard students crammed into a House common room to solicit sex tips from a septuagenarian last night.

The speaker was famed sex therapist Dr. Ruth, who was hosting a question-and-answer session in Cabot House.

Her topics ranged from bawdy to serious—from the definition of oral sex and myths about masturbation on the one hand, to contraception, abortion, and homosexuality on the other.

In her opening remarks, Dr. Ruth set out to expose the truth behind rumors about human sexuality.

“The size of the penis,” she said, “has nothing to do with the sexual satisfaction of a woman—unless it’s miniscule.”

Dr. Ruth, who has written a guide to college life, answered questions that had been submitted anonymously and were then read out by Cabot House Co-Masters Jay and Cheryl Harris.

“Is a blowjob sex?” one of the cards read. The student signed it “Bill Clinton.”

“There’s no question,” Dr. Ruth answered, saying that she counts many kinds of intimate contact as sex. Other anonymous questions asked about monogamy and abstinence before marriage. “I told you, I’m old fashioned and square,” the 78-year-old said.

She added that although she doesn’t mind sex before marriage, “when actually to do it is a question that each person has to decide.”

Before Dr. Ruth’s arrival, several dozen students filled the Cabot Living Room’s couches with anticipation. One group of seniors came early, more than half an hour before the session was scheduled to begin.

Students said they were excited to see the four-foot-seven, nationally renowned author. “I’m here just because I’ll never have the opportunity to see her again,” said Jason B. Munster ’07. “She has a lot of influence in people’s lives, if not mine.”

Associate Dean of Academic Advising Monique Rinere opened the event by introducing Dr. Ruth.

The two had both worked at Princeton, where Dr. Ruth was a visiting professor in spring 2003 while Rinere was serving as one of the school’s deans.

Dr. Ruth, whose full name is Ruth K. Westheimer, was born in Germany, but escaped to Switzerland at age 10, Rinere said.

Dr. Ruth also once taught kindergarten in France and served as a sniper in Haganah, a Jewish paramilitary group. “She’s not just the most famous sex therapist in the United States,” Rinere said.

Dr. Ruth isn’t having a one-night stand with Harvard. She is scheduled to appear this morning at Studies of Women, Gender, and Sexuality 1000, “Introduction to WGS: Women, Men, and Beyond: Gender and Sexuality in an International Frame,” the concentration’s introductory course. Then she will speak at a public event at 4 p.m. in Boylston Hall’s Fong Auditorium, entitled “Dr. Ruth Talks Sex: With Yourself, With Others, and Not at All.”

Dr. Ruth is at Harvard as part of the first Women’s Week, co-sponsored by the Women’s Center and the Seneca.