Methods	Randomised controlled trial
Participants	317 fourth grade school students and their families. 57.4% Male, 33.8% Caucasian
Location	Lancaster, US.
Interventions	Project CARE, a substance abuse prevention program, aimed at improving students’ skills (problem solving, peer resistance) and parents’ skills.
Programme deliverer	Psychologist and prevention specialist
Evaluator role	Independent
Outcomes	Negative behaviours Intent to use substances Alternative activities Communication with parents Substance use School absences, school suspensions, school grades
Length	One school year plus a summer, one session per week
Assessment	Baseline, post treatment, 12‐months follow‐up, 21‐months follow‐up
Attrition	40% (12 months follow‐up) 75% (21‐months follow‐up)
COI statement	Not declared
CoFI	Unlikely