“As a grad student, I invited Junot Díaz to speak to a workshop on issues of representation in literature,” she wrote on Twitter. “I was an unknown wide-eyed 26-year-old, and he used it as an opportunity to corner and forcibly kiss me. I’m far from the only one he’s done this to, I refuse to be silent anymore.”

Ms. Clemmons said she believed that Mr. Díaz had tried to pre-empt accusations like hers by writing the autobiographical essay in The New Yorker last month in which he said that he had been raped as a child by an adult he trusted. In the essay, Mr. Díaz said that after the assault, he began to suffer from depression and “uncontrollable rage,” and later had troubled relationships with women and problems with fidelity.

In a statement provided through his literary agent, Nicole Aragi, Mr. Díaz did not address the specific accusations, but said he took responsibility for his past behavior.

“I take responsibility for my past,” he said. “That is the reason I made the decision to tell the truth of my rape and its damaging aftermath. This conversation is important and must continue. I am listening to and learning from women’s stories in this essential and overdue cultural movement. We must continue to teach all men about consent and boundaries.”