The development, reliability and validity of a new measure of personality and affect, the Comprehensive Personality and Affect Scales (COPAS) was investigated in three studies of college students. In study 1, the factor structure of personality, negative affect, and positive affect was assessed, with five-factors found in each of the three analyses. Fifteen scales (Personality: Emotionality, Extroversion, Openness, Conscientiousness, and Agreeableness; Negative Affect: Depression, Hostility, Agitation, Anxiety, and Social Anxiety; Positive Affect: Contentment, Joy, Love, Vigor, and Excitement) were constructed based on results of the factor analysis. Confirmatory factor analyses confirmed the measurement model. In study 2, the reliability and construct validity of each of the 15 factor-derived scales was assessed in both referred and non-referred college students. Study 3 investigated the utility of the COPAS scales in differentiating referred and non-referred college students. Results indicated that reliability of the scales was good to excellent, while convergent and divergent validity was good for most scales. The COPAS scales were also shown to differentiate between referred and non-referred samples of college students. Overall, the COPAS was shown to be suitable for research with college student populations.