Self-harm behavior is exhibited by a substantial minority of the general population and may be particularly prevalent among adolescents and clinical samples, both in psychiatric and primary care settings. A number of measures are currently available for the assessment of self-harm behavior. These vary a great deal in terms of their content, response options, targeted clinical audience, time to complete, and availability. The Self-Harm Inventory, a measure that we developed for the assessment of self-harm behavior, is one-page in length, takes five or less minutes to complete, and is free-of-charge. Studies indicate that the Self-Harm Inventory does the following: 1) screens for the lifetime prevalence of 22 self-harm behaviors; 2) detects borderline personality symptomatology; and 3) predicts past mental healthcare utilization. Hopefully, more efficient assessment of self-harm behavior will lead to more rapid intervention and resolution.