A history of the achievement levels for the National Assessment of Educational Progress (NAEP) could be documented in different ways. A chronological history might be the obvious approach, but in the author's view, that could miss the most salient aspects of setting student performance standards on an assessment like NAEP. Further, new initiatives are fostered within a social and political context that is critical to understanding the initiative's development, direction, and destiny. Therefore, rather than following a strict chronology, the author has adopted an issues-based approach, describing first the contextual issues that surrounded NAEP during the beginnings of achievement levels in the late 1980s and early 1990s. The paper will then discuss the critical initial implementation decisions made by the National Assessment Governing Board as it developed the student performance standards for NAEP. Then it will follow new implementation issues into the first decade of the 21st century; finally, it will discuss the broad impact of the achievement levels on American education. (Contains 5 figures, 2 tables, and 24 endnotes.) [This paper was commissioned for the 20th Anniversary of the National Assessment Governing Board, 1988-2008.]