The present study examined responses to romantic breakup as a function of relationship contingency of self‐worth (CSW)—the degree to which individuals base self‐worth on being in a romantic relationship. Relationship CSW was hypothesized to be a vulnerability factor, exacerbating affective and behavioral responses to romantic relationship dissolution. Results of structural equation modeling (N = 312) revealed that among participants who reported a breakup over the past year, those who more strongly based self‐worth on being in a relationship reported greater emotional distress and obsessive pursuit of their ex‐partners than did those with lower relationship CSW. Specifically, emotional distress partially mediated the link between relationship CSW and obsessive pursuit. Implications of relationship CSW for interpersonal motivation and well‐being are discussed.