Nonsuicidal self-injury (NSSI) is a growing public health problem among adolescents and young adults. The Inventory of Statements About Self-Injury (ISAS) is a self-report measure designed to assess NSSI behaviors and functions. The current study examines the one-year test–retest reliability of the ISAS in a sample of young adult self-injurers. Results indicate that the ISAS behavioral and functional scales demonstrate good stability over one year. For the behavioral scales, test–retest correlations ranged from .52 (biting) to .83 (burning), with a median of .68. For the functional scales, test–retest correlations were .60 for the superordinate intrapersonal functions scale and .82 for the superordinate interpersonal functions scale. Regarding individual functions, test–retest correlations ranged from .35 (affect regulation) to .89 (peer bonding), with a median of .59. Findings suggest the ISAS has good test–retest reliability and contributes to the growing literature on the psychometric properties of the ISAS.