This randomized, controlled trial evaluated whether a brief educational program (i.e., Scenario-Tailored Opioid Messaging Program [STOMP]) would improve parental opioid risk knowledge, perceptions, and analgesic efficacy; ensure safe opioid use decisions, and impact prescription opioid use after surgery. Parent-child dyads (n=604) who were prescribed an opioid for short-term use were randomized to routine instruction (Control) or routine plus STOMP administered preoperatively. Baseline and follow-up surveys assessed parents’ awareness and perceived seriousness of adverse opioid effects, and their analgesic efficacy. Parents’ decisions to give an opioid in hypothetical scenarios and total opioid doses they gave to children at home were assessed at follow-up. STOMP parents gained enhanced perceptions of opioid-related risks over time while Controls did not; however, risk perceptions did not differ between groups except for addiction risk. STOMP parents exhibited marginally greater self-efficacy compared to Controls (mean difference vs. controls=0.58 [95% CI 0.08, 1.09], p=.023). STOMP parents had a 53% lower odds of giving an opioid in an excessive sedation scenario (odds ratio 0.47 [95% CI 0.28, 0.78], p=.003), but otherwise made similar scenario-based opioid decisions. STOMP was not associated with total opioid doses administered at home. Instead, parents’ analgesic efficacy and pain-relief preferences explained 7%, while child and surgical factors explained 22% of the variance in opioid doses. Scenario-tailored education enhanced parents’ opioid risk knowledge, perceptions and scenario-based decision-making. While this may inform later situation-specific decision-making, our research did not demonstrate an impact on total opioid dosing which was primarily driven by surgical and child-related factors.