This study expands and validates previous research that found a statistical correlation between the amount of daylight in elementary school classrooms and the performance of students on standardized math and reading tests. The researchers reanalyzed the 19971998 school year student performance data from the Capistrano Unified School District (California) and the Seattle Public School District (Washington) to answer questions from the peer review panel. The reanalysis findings are as follows: (1) overall, elementary school students in classrooms with the most daylight showed a 21 percent improvement in learning rates compared to students in classrooms with the least daylight; (2) a teacher survey and teacher bias analysis found no assignment bias that might have skewed the original results; more experienced or more educated teachers ("better" teachers) were not significantly more likely to be assigned to classrooms with more daylighting; (3) a grade level analysis found that the daylighting effect does not vary by grade; (4) an absenteeism analysis found that physical classroom characteristics (daylighting, operable windows, air conditioning, portable classrooms) are not associated with variations in student absenteeism. This seems to contradict claims that have been made about the health effects of daylight or other environmental conditions, as reflected in absenteeism rates of building occupants.These results, which are consistent with the original findings, affirm that daylight has a positive and highly significant association with improved student performance. These findings may have important implications for the design of schools and other buildings. (Appendices contain the survey and data tables.) (EV)