The purpose of the proposed R01 project entitled “Effects of State Laws to Reduce Opioid Diversion on Transitions to Injection Drug Use and HIV/HCV Transmission” is to examine the effects of state laws designed to reduce opioid diversion and misuse on the transition to injection drug use and HIV/HCV infection. These laws vary in content and implementation by state and include state prescription drug monitoring programs (PDMPs), Medicaid policies that may decrease access to prescription opioids such as prior authorization or pharmacy lock-in programs, Medicaid reimbursement of Medication Assisted therapy, and state regulations of pain clinics. The proposed research will explore the influence of laws in three different states, Connecticut, Kentucky and Wisconsin, selected to represent differences in PDMPs, Medicaid restrictions on opioid prescription, and pain clinic regulation. We will also examine the effects of the local context (drug use networks, syringe availability, harm reduction services, relative price and quality of heroin) on the transition to injecting non-prescription opioids and /or heroin injection in three local areas, an urban area, a smaller metropolitan area or suburb, and a rural town and surrounding county, chosen to reflect areas with higher rates of opioid prescription and opioid overdoses. Specific aims include the following: 1) Identify state laws and policies that have been established to decrease opioid misuse and diversion to establish or refute their association with transition to opioid or heroin injection; 2) Identify how local implementation of state laws and policies may contribute to the transition from nonmedical prescription opioid use to injecting prescription opioids or injecting heroin; 3) Compare local factors in urban, suburban and rural areas that affect the riskiness of injection practices such as the availability of clean syringes, density of drug using networks and accessibility of drug treatment programs. The proposed research will use a two-phase (formative and hypothesis testing) mixed methods design comparing the three states and local areas (3 per state, n=9) to examine factors affecting the relationship between prescription opioid laws and policies and the transition to opioid or heroin injection. .