Project Summary The proposed R01, entitled, Tailored Adaptive Mobile Messaging to Reduce Problem Drinking, is submitted to expand on our recently completed R34 grant entitled, Tailored Mobile Messaging to Reduce Problem Drinking (R34AA021502). Despite significant consequences, heavy drinking individuals with non abstinence goals rarely seek treatment. Newer methods such as internet screening and mobile apps provide opportunities to engage and treat this difficult to reach population. We recently completed an R34 study where we developed the first automated comprehensive tailored adaptive (TA) text messaging intervention for problem drinking (PD). We compared TA to different types of automated once a day messaging including: baseline tailored only messaging (TO), loss framed messaging (LF), gain frame messaging (GF), and weekly mobile assessment only (MA). This was done over 12 weeks in a sample of 171 problem drinkers recruited on the internet across the US. All messaging groups outperformed MA on most drinking outcomes, and the TA group had the largest effect sizes on every drinking outcome with an average weekly drink reduction of 9 standard drinks and a reduction of 2 heavy drinking days a week at week 12. Over an 8- month period, 1149 individuals took the web-based screening survey, highlighting the demand for messaging in this population. This study provides initial evidence of the effectiveness of messaging to reduce PD in help-seeking adults across the country. Large scale randomized controlled trials are needed to provide the necessary empirical evidence to validate SMS interventions and to understand moderators of outcome for help seeking heavy drinkers. In a large scale R01 trial, we propose to compare the Tailored Adaptive messaging group (TA; N=300) to the baseline Tailored Only group (TO; N=300) and the weekly Mobile Assessment only group (MA; N=300). All groups will receive messages for a six month period. Participants will complete self-report web-based assessments at Baseline, 1-Month, 3-Months, 6-Months, 12-Months and 18-Months. Participants across conditions will receive weekly MA for 26 weeks. We hypothesize that TA will be superior to MA on all drinking measures at all time periods and TA will outperform TO at all time periods except one month follow-up. Other aims include testing baseline moderators such as alcohol severity and mediators such as message relevance. Overall, if study aims are achieved, we will: 1) have empirical support that TA is an effective intervention for PD and its effects are durable over time; 2) understand whether receiving baseline only tailoring is sufficient or if adaptive tailoring is needed for long-term behavior change; 3) understand the moderators and mediators of outcome in messaging interventions for PD; and 4) be able to disseminate an empirically-supported direct to consumer mobile intervention for PD to anyone with a mobile phone who is not ready to seek in-person care.