Advances in mobile technology provide an opportunity to deliver in-the-moment interventions to individuals with alcohol use disorders, yet availability of effective "apps" that deliver evidence-based interventions is scarce. The authors developed an immediately available, portable, smartphone-based intervention system whose purpose is to provide stand-alone, self-administered assessment and intervention. In this article, the authors describe how theory and empirical evidence, combined with smartphone functionality, contributed to the construction of a user-friendly, engaging alcohol intervention. With translation in mind, the authors discuss how they selected appropriate intervention components including assessments, feedback and tools, that work together to produce the hypothesized outcomes. Abstract published by arrangement with Taylor and Francis.