Opioid use disorder (OUD) continues to be one of the biggest public health challenges of recent history. The early years of what is now called the “Opioid Epidemic” saw primarily prescription painkiller misuse and abuse. Now, however, as the statistics relate, many OUD patients have moved to heroin. This presentation will discuss the confluence of factors that led up to the epidemic, with a focus on the related changes in OUD patients and the treatment challenges these changes present. Data collected from a nationwide network of treatment centers will be presented and treatment implications for this changing population will be reviewed.