After decades of consignment to the periphery of the health care system, substance use treatment will soon become part of mainstream medical care alongside other health specialties. The passage of the ACA (Affordable Care Act 2010) accelerated the trend toward greater integration of behavioral health (including substance use) with primary health care. Several trends in the past two decades contributed to the changing the view of substance use from one that was a purely ‘moral’ problem, rooted in the character deficiencies of substance users to a chronic, relapsing disease that could be treated and managed. Changes were precipitated by four trends: (a) rising cost of substance use, (b) the substance use burden on the criminal justice system, (c) the cost of substance use in the healthcare system, and (d) the growing evidence for the effectiveness of treatment. The paper examines how rising costs in the criminal justice and health care systems spurred changes toward substance use treatment and the role of evidence in legitimizing substance use treatment.