Women, as with men, are in competition with one another to identify, attract, and retain quality mates. Identifying quality mates can be a difficult, risky, and costly endeavor; however, women can usefully draw on the mating preference of other women to inform their own choices. After reviewing theoretical foundations of the benefits of using female conspecifics as sources of information about potential mates, this chapter discusses evidence of mate copying, poaching, and retention behaviors across multiple species and then the parallel evidence emerging for these behaviors in humans. Of particular interest is identifying why women compete with one another for mates and under what ecological conditions such behaviors are more likely to emerge. Understanding these contextual issues leads to suggestions about the psychological mechanisms that enable women to acquire information about other women’s preferences, when that information is utilized, and the strength of social information in shifting women’s mating preferences.