The objective of this research project is to develop an integrated set of digital tools that will deliver a brief motivational intervention (BMI) for young adult marijuana users across a variety of platforms. We have, in four randomized clinical trials, demonstrated the effectiveness of similar tech-based interventions for problem drinking. These interventions have been integrated into one comprehensive program, CheckUpandChoices.com (CC). CC has been commercialized and is in use by the general public and treatment providers. This project will develop and test a new, marijuana-focused component for CC, thus expanding the type and size of the population it can serve. Further, by utilizing an advanced software stack, development of the MCU will entail the development of an iOS/Android mobile application that is integrated with CC. This innovation will enable new features with concomitant methodological advances in the clinical assessment and intervention of target behaviors. Thus, the long-term objective is not just to develop an app that will work across devices and platforms to deliver the MCU, and enhance the overall reach and effectiveness of CC, but further, to develop a clinical tool with the potential to advance the field of tech-based interventions for substance abuse. A major project goal in Phase I is to work with a group of individuals who are concerned about their cannabis use. Our team of clinicians and software engineers will iteratively develop the prototype app and the interface between the app and web-based version of MCU. In this Phase I study, given the limited time frame, our intent is to focus on usability and feasibility. As such, the features we will develop for the prototype will be based on the empirically supported, face-to-face BMI developed by our Consultants. We will, in Phase II, complete its development that includes our research into the clinical benefits of this technology, as well as ongoing advances in technology. The ability of technology to convey interventions to individuals who might not otherwise access treatment presents clinical scientists with a significant opportunity to help those struggling with addiction. The technology also affords methodologies with the potential to significantly advance the fields of behavioral health and clinical psychology. Given the human suffering and financial cost associated with alcohol and substance abuse, this innovation has significant potential to reduce the burden these disorders place on the people who use it, as well as their family and friends, and society at large.