Methods	Cluster‐randomised controlled trial in Dares Salaam, Tanzania Study conducted from 2011 to 2014
Participants	38 public primary schools were randomly selected, half to intervention and half to control. Total of 5091 male and female students (adolescents aged 12‐14) were recruited at baseline, and interviewed again at 6 (n = 4783) and 12 months (n = 4370).
Interventions	Intervention: PREPARE was designed to promote delayed sexual initiation and safer sexual behaviours among adolescents. It consists of 3 components implemented by teachers (6 lessons over 11 h), peer educators (3 lessons over 8 h), and health care providers (linking adolescents to information and services that may foster healthy sexuality). Control: half of the primary schools were assigned to the control group based on their size and geographic location.Setting: school‐level Timing of intervention: Moderators delivering: teachers, peer educators, health care providers
Outcomes	Primary: self‐reported sex initiation and condom use during the past 6 months.
Notes	Funding: EC Health research programme Declaration of interest: The authors declare that they have no competing interests.