While there is much research on what people want in their romantic and sexual partners, the methods are limited in several ways (e.g., ad hoc, limited ecological validity, exploratory). In this pilot study (N = 185), we present and validate a simple, flexible, behavioral, and straightforward way of assessing mating decisions as opposed to mate preferences, economic tradeoffs, or gestalt choices like in speed dating studies. In this method, participants are asked to choose between pairs of traits they might desire in their romantic and sexual partners, and the number of times each trait was chosen is summed. Further, we advance a need-based approach, suggesting that the things people want in their partners serve psychological and physical needs that can be present today and could have been present over evolutionary time. We suggest that seeking or choosing physicality, compassion, competence, and compatibility solve the major challenges presented in relationships like sexual arousal, intra-relational safety, extra-relational safety, and long-term coordination of life, respectively. We replicated effects in relation to sex differences and contexts effects consistent with sexual strategies theory and extended that to show that compatibility is the most highly valued trait in their partners by men and women regardless of context.