In two studies, the authors examined the projection of romantic and sexual desire in opposite-sex friendships. In both studies, perceivers who strongly desired their friends projected this desire onto their friends, believing that their desire was more reciprocated than was actually the case. In turn, projection of desire appeared to motivate perceivers into enacting relationship initiation behaviors, which predicted changes in targets’ romantic and sexual desires over time (Study 2). Projection was elevated for perceivers who saw themselves as high in mate value, and targets appeared to be influenced by perceivers’ overtures primarily when they believed perceivers were high in mate value. This research suggests that, for perceivers high in mate value, romantic and sexual desire creates biased perceptions that initiate self-fulfilling prophecies.