This report evaluates the Okiyapi Community Partnership, a 5-year federally funded program that aimed to reduce alcoholism on the Devils Lake Sioux Reservation in rural North Dakota. The major goals of the project included development of an interagency coordinating body, establishment of family circle groups, and training of Native American addiction counselors. During the first 2 years of the project, five tribal members completed college courses in addiction counseling, with two of the five receiving degrees in addiction counseling. These individuals made up the project's core staff, which facilitated the creation of a stable interagency coalition and implemented prevention awareness activities through four district family circle groups. The coalition, led by Little Hoop Community College, consisted of over 30 members from local schools, the Tribal Council, and various tribal and public agencies. Interagency coordination involved sharing of data and human and material resources, and collaboration in designing, implementing, and publicizing substance abuse prevention activities. Evaluation data included annual community surveys of substance abuse perceptions and prevalence, surveys of high school students, personal interviews with coalition members, reports of daily activities of coalition staff, tribal court statistics, coalition meeting minutes, activity sign-up sheets, and internal and external correspondence related to the partnership. Process and outcome evaluation measures showed evidence of strong interagency coordination in all program aspects, significant increase in community awareness of the program, extensive family involvement in program activities, declines in reported use of alcohol and related problems among youth, community-wide decline in alcohol-related offenses, and changes in tribal law restricting availability of controlled substances. Includes numerous figures and tables. (LP)