What happened to Clare at the end of Passing is ambiguous. When Irene sees Clare's white husband, John Bellew, arrive at the party, Irene dashes across the room. She thinks, "She couldn't have Clare Kendry cast aside by Bellew. She couldn't have her free." Irene is terrified that if John Bellew discovers Clare at the party, he will know that she is African American and will leave her. Clare will then be free to take Irene's husband away from her. Irene definitely has a motive to kill Clare, but so does John Bellew, who is very racist and who has not realized until that moment that his wife is African American. Clare might also have thrown herself out of the window in desperation, as she knows that her life, as she has lived it, is now over. Her secret has been revealed. The author intentionally leaves the ending ambiguous because the reader has to think about the ways racism has affected all these characters and the different forces that have conspired to kill Clare.

The ending of Passing, like the beginning, involves someone falling to the street below in ambiguous circumstances. In the opening chapter, it's a man lying crumpled in a heap on the sidewalk; in the final chapter it's Clare. The main difference is that, although the fate of the man is uncertain, Clare is definitely dead. More to the point, we have no idea who's responsible for her death. One minute she's there, standing by the window, unusually calm despite her husband's angry insults after discovering her racial heritage; the next minute, she's gone. All Irene can say about this tragic incident is that Clare "just fell."

The ambiguity here is deliberate. Clare was someone who lived her whole life never quite knowing who she really was; never being able to feel comfortable in her own skin due to her fateful decision to pass for white. Her sad demise is—appropriately enough—every bit as ambiguous as her identity. Even in death, it seems that Clare doesn't really belong anywhere. That no one's willing or able to describe the manner of her death speaks volumes about the treatment of someone in her position in this race-conscious society. In death, as in life, people like Clare are denied the opportunity to have their stories told.

In Nella Larsen's novel about racial identity, Passing, there is no focus on discovering who is guilty of Clare's fall from the upper window. The idea of what happens is left up to the reader, so that conclusions can be made from the perspectives of the different characters.

It is highly unlikely that Clare's husband would want to do something like that to Clare because he was indifferent to her in many ways. It would hardly be a crime of passion, nor a crime of hatred: He simply does not pay enough attention to his wife to decide whether he loves her or not. Those who do not love, would not care to hate.

Clare enjoys life too much, especially its carnal pleasures, to end her life just for a moment of despair. As a woman who seeks pleasure in every way, Clare is more than able to surpass any heavy situation by switching to an alternative way to have a good time. Like, when her husband stops paying attention to her, she simply goes and finds another man.

Hence, the last alternative and the most feasible we have is that Irene either pushed Clare or caused the scenario for Clare to fall. We know this because the words that are used to describe Irene's feelings denote that Clare's death makes Irene feel liberated. She feels liberated from living under Clare's shadow, from feeling threatened by Clare's intense sexuality, and from fearing that Clare will take every bit of dignity away from Irene.

Therefore, the one person who mostly benefits from Clare's death is Irene. We can conclude that it is Irene who is responsible for Clare's fall.