This investigation examined the extent to which students with disabilities are involved in a select sample of national data collection programs that are playing a pivotal role in the measurement-driven educational reform movement. Nine data collection programs that are receiving significant attention in current educational reform initiatives were reviewed. The results suggest that approximately 40% to 50% of school-age students with disabilities are excluded from some of the most prominent national educational data collection programs. In contrast, students with disabilities are included to a greater degree in noneducational data collection programs that do not require participation in direct assessment activities. This study reports on the extent of exclusion, how and why exclusion occurs, and the impact of this exclusion on policy research. Preliminary recommendations for addressing the significant exclusion of students with disabilities from certain national data collection programs are presented.