The transition from a platonic cross-sex friendship to a more intimate sexual and/or romantic relationship is an interesting, yet somewhat understudied, phenomenon. In this study, we introduce and test relationship adaptation theory to predict cross-sex friends' predispositions for reciprocating a bid for escalation to an exclusive dating or friends with benefits (FWB) relationship. Analyses of data collected from 288 participants found participants' dating status, anticipated rewards from escalating the relationship, expected social disapproval, friendship quality, and their friend's attractiveness predicted disposition to reciprocating a cross-sex friend's hypothetical bid for escalation to an exclusive romantic escalation. In addition, participants' biological sex, anticipated rewards from escalating the relationship, expected social disapproval, sexual permissiveness, and their friend's attractiveness emerged as predictors of disposition toward a friend's hypothetical bid to escalate a platonic friendship to a FWB relationship.