The purpose of this study was to compare teachers and parents as instructors of a personal safety program. One hundred seventy-two Head Start preschoolers were randomly assigned to a personal safety program taught by their teachers, parents, both teachers and parents, or to a general safety control program. Following program participation, children taught the personal safety program by their teachers, parents, or both, demonstrated greater knowledge about sexual abuse and higher levels of personal safety skills compared with those in the control group. Gains in knowledge and skills were maintained at the 5-month follow up. Children taught by their parents showed greater improvements in recognizing inappropriate-touch requests and in their personal safety skills compared with children taught by their teachers, and children who received the program both at home and school were better able to recognize appropriate-touch requests and to demonstrate higher levels of personal safety skills compared with children taught only at school. The emotional costs associated with participating in the program were minimal, and both parents and children rated the program positively. The advantages of home-based instruction for young children are discussed and suggestions for future research are offered.