"He said to me, "I thought you had an orgasm", she said.
Mr. Cosby has denied assaulting all of the women and has said that the sexual encounter with Ms. Constand was consensual.
Cosby, 80, once a beloved stand-up comedian and television star known for his family-friendly material, is on trial in a Pennsylvania court on charges of drugging and sexually assaulting another woman, Andrea Constand, in 2004.
They went to a room, and she began to feel lightheaded and couldn't get the right words out, she testified. But the defense has since brought forward two former Temple colleagues of Constand's who said she knew Jackson.
It's expected that during Constand's cross-examination that the defense will set her up to discuss one of their key witnesses, Marguerite Jackson, a former co-worker of Constand's at Temple University.
The case has besmirched the legacy of the actor once adored by millions as "America's Dad" for his role as lovable father and obstetrician Cliff Huxtable on the hit 1984-92 television series "The Cosby Show". Even his "confessions" in the civil trial may simply prove he administered these drugs, but to what end?
She alleged that after Cosby assaulted her he told her: "Now this is just between you and me". This time the prosecution has been allowed to admit the testimony of five other women who have accused Cosby of sexual misconduct.
"I was very scared...because he was a Temple trustee, a powerful man, an entertainer, a very famous person", Constand told jurors about reporting the assault to police.
Cosby's attorneys are expected to cross-examine Constand, including about the almost $3.4 million settlement she received.
KELLY: So Andrea Constand took the stand today.
Dickinson, now 63, was a supermodel in 1982 and said Cosby flew her out to Lake Tahoe, a resort area on the California-Nevada border, to meet her.
"She was madly in love with his fame and money". She says she was still incapacitated and "was not able to do anything" about the assault. "The main goal was to make Cosby uncomfortable because that is exactly what he has been doing for decades to women", she said afterward. "Constand kept coming to see him and not one time did he go to see her".
Her harrowing account of sexual molestation was remarkably similar to the one she gave at last year's trial, and jurors watched intently and scribbled notes as she described how Cosby - the good-guy celebrity she viewed as a mentor and friend - had betrayed her trust.
Unlike Cosby's first sexual assault trial - which ended in a mistrial a year ago after a tied jury failed to reach a verdict - the judge is allowing five accusers to testify against the TV star and stand-up comedian. Cosby paid Constand almost $3.4 million over a decade ago.
Defense attorney Kathleen Bliss asked her about testimony and prior statements, in an apparent attempt to point out inconsistencies about her comments about sitting between Cosby's legs. She said Cosby invited her to his house in Cheltenham, Pa.to talk through how she would break the news to her boss. He predicted that, when the jury hears Constand's testimony in full, they will ultimately find Cosby not guilty of these crimes.
The Associated Press does not typically identify people who say they are victims of sexual assault unless they grant permission, which Constand has done.
It's Constand's second chance to confront Cosby in court, since his first trial ended without a verdict.