Pré-publication, Document de travail: This paper explores the implications of profile information on female participation and ethnic sorting. In the context of the world’s leading peer-to-peer car-sharing platform, BlaBlaCar, I leverage a novel data set that contains detailed information on users and transactions in the routes connecting eight of France’s largest cities. Using a structural framework that accommodates the main strategic decisions of both market sides, this paper shows that women prefer to travel with other women and that there exists a substantial degree of ethnic-based homophily. This paper also provides evidence that alternative designs limiting the sorting abilities of users do not necessarily benefit ethnic minorities and that women from the ethnic majority tend to be the population segment whose participation and welfare reduces the most when anonymous marketplaces are imposed.