In 1979, the Western Interstate Commission for Higher Education (WICHE) began its high school graduates by state projections. The three editions issued since that time have been widely used. This report provides an analysis of the accuracy of the WICHE's projections and an examination of the cohort survival method used to generate the projections. This method assumes that enrollments and graduates can be projected by measuring the survival or transition of birth cohorts into first grade, and then from one grade to the next. The first section of the report compares the WICHE's 1988 projections by state with the number of actual graduates reported through 1990-91 and with projections by the National Center for Education Statistics. The second section discusses the Mean Absolute Percentage Error (MAPE) achieved using the cohort survival method for all 50 states and the District of Columbia. The WICHE's figures have closely followed actual trends in graduation. The 1988 projection series varied less than 1 percent from the actual number of graduates for 1988 and 1989; and 1.5 and 2.3 percent, respectively, for 1990 and 1991. Four tables and one graph complement the discussion. (SLD)