The tribal list frame consisted of 292 tribal health organizations, and was developed by IHS through a compilation of multiple listings and a careful review of each tribe’s service type and contact information. Of the 292 entities, 12 were MTAHB and were selected with certainty for the final sample. The remaining 280 tribal entities formed the frame for the tribal health organization sample. The list was sorted by service type (Direct Service, Title I, Title V)4, user population size (small, medium, large), region, and state. The final sample consisted of 102 tribal health organizations, and was equally distributed by region, size, and service type.