In this study, the authors examined the psychometric properties of the key cognitive strategies (KCS) within the CollegeCareerReady[TM] School Diagnostic, a self-report measure of critical thinking skills intended for high school students. Using a cross-validation approach, an exploratory factor analysis was conducted with a randomly selected portion of the sample (n = 516) and resulted in five reliable factors: (a) problem formulation, (b) research, (c) interpretation, (d) communication, and (e) precision/accuracy. A confirmatory factor analysis was conducted with the remaining sample (n = 808). Goodness-of-fit indices indicated acceptable model fit. The five-factor solution is consistent with earlier validity studies of the KCS framework. Implications for use by high school personnel in evaluation of instructional programs and as a value-added assessment are discussed. (Contains 2 figures, 2 tables, and 1 note.)