This study reports on the reliability and concurrent validity of both the trait and state forms of the Multiple Affect Adjective Check List (MAACL) with a high school population, age range of 14-16 years and educational range of 9th and 10th grades (N = 403). Alphas of the four scales (anxiety, depression, hostility, and positive affect) ranged from .67 to .91. Correlations with a check-list of stress-related symptoms and an inventory of the number of extracurricular activities in which the students participated were significant and in the expected direction. Means and standard deviations on the MAACL scales were similar to those of college students. Sex differences were found on some of the scales. The findings indicate that the MAACL is sufficiently reliable and valid to warrant additional use with an adolescent population.