Understanding of preadolescent sexuality is limited. To help fill this gap, we calculated frequencies, percentages, and confidence intervals for 1,096 preadolescents' reports of sexual thoughts, intentions, and sexual behavior. Cochran-Armitage trend tests accounted for age effects. Findings show that 9-year-olds are readying for sexual activity, with sexual readiness increasing between ages of 9 and 12. Sexual thoughts increased with age (p less than 0.001): 46% of 9-year-olds and 70% of 12-year-olds were ready to learn about sex, and 14% of 9-year-olds and 41% of 12-year-olds thought about having sex. Few 9-year-olds anticipated sexual debut, but this increased with age (p less than 0.05): 25% of 12-year-olds were ready for sex, and 20% anticipated initiating sex within a year. Our results indicate that preadolescents are initiating dating relationships and anticipating intercourse, and some have engaged in risk behaviors. Thus preadolescence is a critical time to implement prevention programs. (Contains 1 table.)