Mothers’ observations (N = 670) of child sexual behavior have been collected using an adapted version of the Child Sexual Behavior Inventory as developed by Friedrich et al. (1991). The ages of the boys (N = 351) and girls (N = 319) observed range from 0 to 11 years. The results show that there is a lot of variance in the frequency with which specific sexual behaviors are observed. The occurrence of specific behaviors varies with age. While some behaviors are observed more frequently as the child gets older, others are observed less frequently. Boys and girls only differ in a few behaviors. The finding that the behavioral items form an internally consistent scale suggests that there is a general tendency to show sexually related behaviors, which is more or less strongly present in children, which might be a precursor of differential levels of sexual desires in adults.