This dissertation takes a multi-level approach to understanding the extent to which the relationship between drugs and society has evolved over the past twenty years by looking at macro, state-level changes in the policy environment along with changes in the services provided by drug treatment organizations. I begin by examining the diffusion of Good Samaritan and Naloxone Access laws: two state-level policy reforms, which reflect an overall shift towards the medicalization (rather than criminalization) of opioid addiction. With this changing policy landscape as a background, I investigate whether this increased concern with treating opioid addiction as a health issue is also reflected in the availability of three kinds of drug treatment services relevant to people who are dealing with opioid addiction: methadone, buprenorphine, and treatment for co-occurring mental health issues. Consequently, this dissertation seeks to answer three separate (yet interrelated) questions that address the extent to which the US is shifting to addressing drug addiction as health problem and the reasons for these changes: 1) Why have Good Samaritan and Naloxone Access laws diffused, and why are their diffusion patterns different?; 2) How have medicalized opioid addiction treatment services diffused in the last 20 years?; and 3) Do factors predicting the availability of medical-based treatment services vary over time or by type of treatment? While medicalized drug policies and practices have all diffused widely, this diffusion has not bee uniform – with Naloxone laws diffusing more than Good Samaritan laws, Buprenorphine diffusing more than Methadone, and treatment for co- occurring mental health issues diffusing more than medication-assisted treatment. In total, my dissertation makes three key arguments. First, understanding how policies and practices alter definitional and institutional loci of social problems is integral to understanding the diffusion of policy and practices. Second, policies or practices that expand institutional domains diffuse wider than those that challenge institutional logics. Finally, institutions and their responses to social problems are racialized – possible solutions to a social problem and the institutional context of these solutions depends on whether whites or non-whites are seen as the affected population.