Child sexual abuse (CSA) interventions draw from a better understanding of the context of CSA. A survey on violence before age 18 was conducted among respondents aged 13–17 and 18–24 years. Among females (13–17), the key perpetrators of unwanted sexual touching (UST) were friends/classmates (27.0%) and among males, intimate partners (IP) (35.9%). The first incident of UST among females occurred while traveling on foot (33.0%) and among males, in the respondent’s home (29.1%). Among females (13–17), the key perpetrators of unwanted attempted sex (UAS) were relatives (28.9%) and among males, friends/classmates (31.0%). Among females, UAS occurred mainly while traveling on foot (42.2%) and among males, in school (40.8%). Among females and males (18–24 years), the main perpetrators of UST were IP (32.1% and 43.9%) and the first incident occurred mainly in school (24.9% and 26.0%), respectively. The main perpetrators of UAS among females and males (18–24 years) were IP (33.3% and 40.6%, respectively). Among females, UAS occurred while traveling on foot (32.7%), and among males, in the respondent’s home (38.8%); UAS occurred mostly in the evening (females 60.7%; males 41.4%) or afternoon (females 27.8%; males 37.9%). Among females (18–24 years), the main perpetrators of pressured/forced sex were IP and the first incidents occurred in the perpetrator’s home. Prevention interventions need to consider perpetrators and context of CSA to increase their effectiveness. In Kenya, effective CSA prevention interventions that target intimate relationships among young people, the home and school settings are needed.