Years of attraction research have established several "principles" of attraction with robust evidence. However, a major limitation of previous attraction studies is that they have almost exclusively relied on well-controlled experiments, which are often criticized for lacking ecological validity. The current research was designed to examine initial attraction in a real-life setting-speed-dating. Social Relations Model analyses demonstrated that initial attraction was a function of the actor, the partner, and the unique dyadic relationship between these two. Meta-analyses showed intriguing sex differences and similarities. Self characteristics better predicted women's attraction than they did for men, whereas partner characteristics predicted men's attraction far better than they did for women. The strongest predictor of attraction for both sexes was partners' physical attractiveness. Finally, there was some support for the reciprocity principle but no evidence for the similarity principle.