This report is the first phase of a larger project to generate indicators of disparities in care and unmet need in Alaska. It provides prevalence estimates of serious behavioral health disorders. Prevalence estimates provide a standardized basis for defining the need for services in a population. The second phase of this larger project assesses the number of individuals who actually receive services. The third phase combines the information to generate indicators of unmet need and disparities in care. The project is an initiative of the Division of Behavioral Health (the Division) of the Alaska Department of Health and Social Services. The Division contracted with the Western Interstate Commission for Higher Education (WICHE) Mental Health Program to facilitate the project. Phase I prevalence estimates were generated by an epidemiologist who has developed a technology specifically for this purpose. The synthetic estimation technology has been used for mental disorders by ten western states; Alaska is the first to use the substance use estimates.