An important assumption in interpersonal attraction research asking participants about their ideal partner preferences is that these preferences play a role in actual mate choice and relationship formation. Existing research investigating the possible predictive validity of ideal partner preference, however, is limited by the fact that none of it has focused on the actual process of relationship formation. The current research recruited participants when single, assessed ideal partner preferences across 38 traits and attributes, tracked participants’ relationship status over 5 months, and successfully recruited the new partners of 38 original participants to assess their self-evaluations across the same 38 traits and attributes. Using multilevel modeling to assess the correspondence between ideal partner preferences and self-evaluations within couple, the results showed a positive within-couple association that was not accounted for by personality similarity or stereotype accuracy. We discuss these results with respect to the current literature on the predictive validity of ideal partner preferences in relationship formation.