The first essay in my dissertation investigates the impact of a state policy designed to reduce substance abuse. Prescription drug monitoring programs (PDMPs) are state-run electronic databases that track the prescribing and dispensing of controlled substances. I examine the impact of PDMP implementation on various measures of opioid pain reliever abuse. I estimate difference-in-differences models, and address possible policy endogeneity by controlling for pre-implementation trends and related state laws. The preferred estimates suggest that PDMPs reduced opioid abuse treatment admissions by 13.1%. However I cannot reject the null hypothesis that PDMPs had no effect on self-reported nonmedical use and overdose deaths. The second essay inves...