While there is a limited data on safety-sensitive professionals, substance use disorders potentially affect pilots and flight attendants at the same rate as the general population – around 15 percent – but due to the high-risk nature of their jobs, aircraft operators are held to a higher standard for substance misuse on the job.To protect the safety of the public and the aviation workforce, the Human Intervention Motivation Study (HIMS) and the Flight Attendant Drug and Alcohol Program (FADAP) were launched to help treat critical aviation workers – pilots and flight attendants, respectively – who misuse substances. In response to a congressional mandate, this new report reviews available evidence on the effectiveness of HIMS and FADAP and offers recommendations for improving these programs.