The issue of what type of juvenile offender produces an invalid versus a valid Minnesota Multiphasic Personality Inventory, Adolescent Form (MMPI-A) profile requires study. Using technical manual profile invalidation requirements from a cohort sample of 1,054 juvenile offenders, 387 produced invalid profiles, whereas 667 yielded valid profiles. Utilizing scale scores from the Millon Adolescent Clinical Inventory (MACI), univariate and multivariate analyses for girls, boys, and combined samples of invalid and valid MMPI-A profiles suggested similarities and differences which influenced the results for the combined samples. The groups were separated on the following MACI scales: Disclosure, Impulsivity, Substance Abuse Propensity, Unruly, and Oppositional by sex and for the combined group. Also noted were other MACI scales which distinguished boys and girls in comparisons made between as well as within the invalid and valid profiles.