The Centers for Disease Control have recently described opioid use and resultant deaths as an epidemic. At this point in time, treating this disease well with medication requires skill and time that are not generally available to primary care doctors in most practice models. Suboptimal treatment has likely contributed to expansion of the epidemic and concerns for unethical practices. At the same time, access to competent treatment is profoundly restricted because few physicians are willing and able to provide it. This "Practice Guideline" was developed to assist in the evaluation and treatment of opioid use disorder, and in the hope that, using this tool, more physicians will be able to provide effective treatment. Although there are existing guidelines for the treatment of opioid use disorder, none have included all of the medications used at present for its treatment. Moreover, few of the existing guidelines address the needs of special populations such as pregnant women, individuals with co-occurring psychiatric disorders, individuals with pain, adolescents, or individuals involved in the criminal justice system. This Practice Guideline was developed using the RAND Corporation (RAND)/University of California, Los Angeles (UCLA) Appropriateness Method (RAM) - a process that combines scientific evidence and clinical knowledge to determine the appropriateness of a set of clinical procedures. The RAM is a deliberate approach encompassing review of existing guidelines, literature reviews, appropriateness ratings, necessity reviews, and document development. For this project, American Society of Addiction Medicine selected an independent committee to oversee guideline development and to assist in writing. American Society of Addiction Medicine's Quality Improvement Council oversaw the selection process for the independent development committee. Recommendations included in the guideline encompass a broad range of topics, starting with the initial evaluation of the patient, the selection of medications, the use of all the approved medications for opioid use disorder, combining psychosocial treatment with medications, the treatment of special populations, and the use of naloxone for the treatment of opioid overdose. Topics needing further research were noted.