The goal of this treatment development project is to develop an adaptive ecological momentary intervention (a-EMI) for young adults using marijuana and alcohol that is grounded in self-regulation and social cognitive theories. To determine the most efficacious intervention strategies, the investigators will test variations of intervention components to identify the best combination. The study will take place at the Center for Integrated Health Care Research at Kaiser Permanente Hawaii (KPHI), located in Honolulu (island of Oahu). Following pilot testing with 6 participants, the study team will assess the feasibility and efficacy of intervention components on two primary outcomes (negative consequences and protective behavioral strategies \[PBS\]) using a fractional factorial experimental design, with post-intervention assessment and one- and three-month follow-ups. 136 diverse young adults recruited from KPHI who report current simultaneous alcohol and marijuana (SAM) use will be randomly assigned to one of eight groups, representing experimental conditions that include or do not include intervention strategies focused on craving reduction and PBS. As a result of this process, individual and/or combined components that lead to improved outcomes will be retained in a subsequent randomized controlled trial, while ineffective components will be eliminated.