The present investigation was aimed at exploring the stability of the standard score distributions on the GED (General Educational Development) Tests taken by U.S. high school seniors in equating studies conducted by GED Testing Service during the span of 5 years from 2001 (the norming year) to 2005. Three questions were addressed by this exploration: First, are the characteristics of the norming sample representative? Second, have self-reported characteristics of high school seniors changed since 2001, the year of standardization/norming of the new test series? Third, are there any trends in test performance during these years that suggest high school seniors are mastering the content of the GED Tests or are otherwise becoming ignorant of the content? (Contains 22 figures.)