While recent studies have suggested that the timing of sexual initiation within a couple's romantic relationship has important associations with later relationship success, few studies have examined how such timing is associated with relationship quality among unmarried couples. Using a sample of 10,932 individuals in unmarried, romantic relationships, we examined how four sexual-timing patterns (i.e., having sex prior to dating, initiating sex on the first date or shortly after, having sex after a few weeks of dating, and sexual abstinence) were associated with relationship satisfaction, stability, and communication in dating relationships. Results suggested that waiting to initiate sexual intimacy in unmarried relationships was generally associated with positive outcomes. This effect was strongly moderated by relationship length, with individuals who reported early sexual initiation reporting increasingly lower outcomes in relationships of longer than two years.