Since 1971, nearly four million adults have qualified for a high school equivalency credential based on General Educational Development (GED) test results. During Spring 1980 two major studies were undertaken by the GED Testing Service: (1) the U.S. High School Norming Study involving the administration of the GED Tests to a representative sample of U. S. high school graduating seniors and (2) the National Survey of GED Examinees (adults). Results of these two studies provided the data for this study, which comparerd the performance on the GED tests of graduating high school seniors and GED examinees. The percentiles and average standard scores for GED examinees show achievement levels only slightly below the levels for graduating high school seniors. Detailed analyses indicated that graduating high school seniors outperformed GED examinees in 20 of the 22 test content areas in the GED battery. Statistically significant differences occurred in the areas of Capitalization and Punctuation, Usage, and Sentence Correction on the Writing Skills test, and Algebra on the Mathematics test. GED graduates outperformed graduating high school seniors in 18 of the 22 content areas in the GED battery. Statistically significant differences occurred in the areas of General Reading and Prose Literature on the Reading Skills test. However, the magnitude of the differences between graduating high school seniors and GED graduates was small. (Author/JAZ)