PROJECT SUMMARY Alcohol misuse negatively affects relationships and is significantly correlated with higher rates of relationship conflict, distress, and dissolution as well as other serious negative interpersonal consequences (e.g., domestic violence, sexual assaults). Encouragement from concerned partners (CPs) is a common motivator for those who misuse alcohol to pursue care and often the most helpful mechanism in supporting change. The goals of this proposal are to: Identify how specific CP behaviors influence their partner’s alcohol craving, motives, drinking, and problems on a daily basis using dyadic ecological momentary assessment techniques (Aim 1); use the knowledge from EMA analysis to iteratively develop a CP-focused web-based intervention (WBI) that provides psychoeducation about communication patterns that influence DP drinking and by integrating personalized feedback about CPs’ own communication behaviors that may be working against their goals (Aim 2); and pilot the WBI’s efficacy on CP outcomes (depression, anxiety, social support), their partner’s drinking behavior (alcohol consumption, motives, related consequences), and both partners’ relationship distress and conflict (Aim 3). We expect the WBI will yield significant improvements in all outcomes. This project is significant because intervening with CPs has strong potential to change relationship dynamics that may reduce problems and prevent future problems associated with alcohol misuse. It also develops a new prevention model that does not rely on the drinking partner attending a clinical facility to access care. The proposed study is innovative because it uses dyadic and ecological momentary assessment designs to test dynamic questions about interdependence in relationship interactions and alcohol use between partners and employs the generated knowledge to inform intervention adaptation. Teaching CPs to effectively communicate their concerns may be a necessary catalyst for decreasing their partner’s alcohol use and preventing alcohol use disorders. The potential reach of this intervention is large such that it can be easily implemented over the web to those who may need help but would not otherwise seek care.