This purpose of this study was to evaluate the reliability and validity of the Measure of College Students' Organizational Skills (MCSOS), a self-report measure of organization skills of college students. The 60 item measure was administered to a representative sample of 692 freshmen, sophomores, juniors, and seniors from a four-year university, 95 of whom had documented learning disability (LD) and/or attention deficit/hyperactivity disorder (AD/HD). Internal consistency reliability was .9383 for the total scale and ranged from .81 to .87 for the conceptual subscales and from .76 to .92 for the empirical factors. Construct validity was evaluated by factor analysis and differences between the non-disabled and disabled samples. The factor structure was similar but not identical to the conceptual subscales. Group differences were evident between students with and without disabilities, and within disability groups. Overall, the instrument has strong reliability and moderate construct validity. Further work should include confirmatory factor analysis to clarify factor structure.