The current retrospective archival study investigated the patterns of normative sexualized behavior (NSB), problematic sexualized behavior (PSB), and sexual perpetration for three age cohorts of boys and girls in a high-risk child welfare sample. All children in the present sample had exhibited some form of PSB in the past. We hypothesized that the incidence rates (IR) of NSBs would increase linearly from the early childhood cohort (Ages 2/3-7) to the middle childhood cohort (Ages 8-11) to the preadolescence/adolescence cohort (Ages 12-17), for girls and boys. Although the base rate of sexual behaviors generally increases as children age, children tend to hide sexual behaviors starting at an early age. We therefore hypothesized that a concave quadratic trend would be evident for most PSBs. We further predicted that older children would have a greater incidence of PSB, as well as more victims, compared with younger children. We found the predicted upward linear trend for NSB for both girls and boys, with minimal IR differences between the early childhood and middle childhood cohorts. IRs were remarkably high and comparable across age groups for both boys and girls, with respect to the same three PSBs. For the two perpetration history variables, there was a concave effect, with girls and boys in the middle childhood cohort exhibiting the lowest IR. Results are explained in the context of previously established patterns of sexualized behavior, as well as the reporting of such behaviors.