The opioid epidemic is a major concern in communities throughout Massachusetts. ICH is using electronic medical record data to examine prescription opioid use and addiction among a primary care population of youth and young adults in an urban safety-net setting. We will estimate the prevalence and timing of opioid use disorder in relation to initiation of opioid therapy (via prescriptions) and examine patient characteristics that are associated with higher rates of addiction. Our research will help shape provider prescribing practices and augment the limited research on opioid prescriptions in a primary care setting.