Abstract Cannabis use is widespread and associated with worsened prognosis for young adults with first-episode psychosis (FEP). Few cannabis harm reduction interventions have been evaluated for this population, despite potential to improve outcomes in those not ready for cannabis abstinence/reduction-focused interventions. This study aimed to determine a) the acceptability of a digital harm reduction intervention, the Cannabis Harm-reducing App to Manage Practices Safely (CHAMPS) and b) the feasibility of conducting a trial comparing FEP-specialized early intervention services (EIS)+CHAMPS versus EIS-only with this population. We conducted a multi-site pilot randomized controlled trial comparing both arms in 101 young adults (18 - 35 years old) with...