This study aimed to explore the effectiveness of a teacher-based child sexual abuse prevention program entitled "I am learning to protect myself with Mika." The sample consisted of 290 children, their parents, and their classroom teachers. The participants were randomly assigned to intervention (n = 137) or wait-list comparison groups (n = 153) by classroom. The age of the children ranged from 46 to 71 months (M = 58.99, SD = 6.64). The prevention program was a 5-week program that consisted of five modules, including emotional awareness, good touch-bad touch, and body safety rules. To investigate the effectiveness of the prevention program, a latent Markov analysis was conducted. A three-class solution was identified as the best model: Status-1 (self-protecting group), Status-2 (risky secret keepers), and Status-3 (risk group). Following the intervention, members of the two at-risk groups (Statuses 2 and 3) were more likely to move into the Status-1 group than were those participants who had not received the intervention (wait-list comparison). Self-protection skills were analyzed using a 2 x 2 ANOVA with repeated measures. The increase in self-protection skills was greater for participants in the intervention group than for those in the wait-list comparison group from pre-test to post-test. Two-month follow-up analysis showed that gain in knowledge and skills was maintained. This program should be considered as a potential approach to meeting the need for child sexual abuse preventive efforts in Turkish preschool curriculum.