This project investigates how environmental characteristics impact where, why, and for whom substance use treatment delivered via mobile technologies may be more effective in one place versus another. Substance use diagnosis represents a growing threat to public health in the U.S. and globally, but access to effective substance use treatment remains a challenge. Mobile technologies such as smartphones promise broad treatment access, but it is unclear how treatment effectiveness may vary across populations, neighborhoods, and environments. This research shows how different types of neighborhood and environmental characteristics can impact mobile technology-delivered substance use treatment, advancing individualized treatment customization, improving treatment effectiveness, and reducing the public health burden of substance use. This research leverages the results of a large randomized clinical trial of a mobile health substance use treatment to advance understanding of environmental impacts on substance use behavior change. Geospatial analysis of environmental and behavioral data provides empirical evidence to indicate how exposures to geographic factors in both the residential neighborhood and during daily travel impact the attitudinal and behavioral mechanisms and outcomes of treatment. This research advances the design and testing of technology-delivered substance use treatment and other behavioral health treatments by integrating geospatial data collection and analyt