Methamphetamine (METH) is a debilitating and frequently abused substance that is often comorbid with HIV infection. HIV+ persons with current METH abuse or dependence (HIV+/METH+) have several characteristics, in addition to their substance use, that make them particularly susceptible to nonadherence to antiretroviral treatment (ART) including elevated rates of neurocognitive impairment, co-occurrence of psychiatric disorders, and unstable living situations. We propose an intervention development study designed to address these potential mechanisms of nonadherence with the following Specific Aims: 1) To further develop and refine a personalized, automated, real-time, mobile phone, text messaging intervention (iTAB) designed to improve adherence to ART medications among HIV+/METH+ persons; 2) To evaluate the acceptability and effectiveness of a brief psychoeducation plus text messaging intervention (iTAB) as compared to psychoeducation alone (CTRL) for the improvement of objectively measured medication adherence among HIV+/METH+ persons; and 3) To examine predictors of within-person trajectories of nonadherence using the longitudinal data collected over the study. In order to realize these aims, we will leverage the infrastructure of two unique UCSD resources increasing likelihood of study success, impact, and innovation: 1) the Translational Methamphetamine AIDS Research Center (TMARC), which is a NIDA-funded center that focuses on the combined effects of METH and HIV infection, and 2) the California Institute for Telecommunications and Information Technology (Calit2), which conducts research on state-of-the-art wireless means of health promotion. Initially, we will refine the iTAB intervention to ensure that it is user-centered and tailored to the needs of HIV+/METH+ persons via focus groups and rapid prototyping. Once refined, the proposed iTAB intervention will use text messages that are automated, scalable, personalized, interactive, flexible, and motivating. We will assess the acceptability and effectiveness of iTAB in improving objectively measured adherence (i.e., MEMS caps) over a 6-week period via a pilot RCT with 40 HIV+/METH+ assigned to the iTAB intervention and 20 HIV+/METH+ assigned to a psychoeducational control. Predictors of nonadherence including frequency of METH use, neuropsychological impairment, and mood will be examined to determine whether iTAB is better able to compensate for these factors associated with nonadherence as compared to CTRL. Further refinement to the iTAB intervention will be made in order to pursue a large-scale R01 using our tailored intervention.