Using data from Achieving the Dream: Community Colleges Count, this issue looks at changes in cohort composition. The analysis addresses the changing composition of the Achieving the Dream student cohorts from 2002 to 2005. The data show that at Achieving the Dream colleges, the percentage of Hispanic students increased over the four cohorts studied, as did the percentage of students who received Pell Grants and the percentage of students referred to developmental education. Being sensitive to such variations will help colleges interpret results from their strategies, because changes in cohort composition can inform evaluations of intervention strategies over time. (Contains 6 footnotes and 2 figures.)