The specific aims were as follows: (1) Conduct ethnographic research on the methamphetamine market in Ohio; (2) Enrich these data using Ecological Momentary Assessment (EMA), collecting self-report data on daily drug consumption, production, sales, decisions, strategies, etc.; (3) Inform simulation parameters using a panel survey of 204 active methamphetamine users; (4) Construct a computer lab of agent-based model (ABM) simulations to reproduce how the local methamphetamine market operates, integrating both social (i.e., health) and economic behaviors; and (5) Experiment with the ABM simulations to understand how the market operates and functions, create and test policy-based intervention scenarios (e.g. enforcement, treatment, and outreach) intended to impact outcomes, and model risk behaviors (e.g., needle sharing, trading drugs for sex) influencing the spread of HIV among men and women. Case Western University did the data collection, while RTI developed an ABM of methamphetamine consumption. The results eventually became a model to understand the dynamics of methamphetamine use.