There is considerable debate about the assessment of psychopathic traits in adolescence due in part to questions regarding the stability of traits. We investigated the 6-month stability of psychopathic traits in a sample of 83 male adolescent offenders using an augmented protocol for the Psychopathy Checklist: Youth Version and the self-report Antisocial Process Screening Device. Findings suggested moderate to high stability of psychopathic traits, as indexed by total scores, and low to moderate stability of psychopathic traits at the factor level. The interpersonal and behavioral traits demonstrated greater stability relative to the affective traits, and stability varied by developmental stage, with lower stability in early adolescence. Implications for understanding the developmental expression of psychopathic traits in adolescence, as well as for clinical-forensic practice, are discussed.