Adolescents (24 boys, 37 girls) from public school settings were given the MMPI-A on 2 occasions with approximately 1 year between testing sessions. Long-term stability of validity, clinical, content, supplementary, and the new Psychopathology Five scales are examined and correlation coefficients are presented. The reliabilities of the MMPI-A scales are consistent with previously reported data. In addition, improvements made during development of the MMPI-A may have led generally to modest increases in stability of the clinical scales for adolescents. Given the importance of both short-term and long-term test-retest data in the evaluation of the validity of an assessment instrument, this study represents an important step in evaluating the validity of the MMPI-A for assessment of personality.