This study describes the psychometric properties of the Inventory of Motivations for Suicide Attempts (IMSA). The IMSA was designed to comprehensively assess motivations for suicide emphasized by major theories of suicidality. The IMSA was administered to two samples of recent suicide attempters, undergraduates (n = 66) and outpatients (n = 53). The IMSA exhibited a reliable two-factor structure in which one factor represented Intrapersonal motivations related to ending emotional pain, and the second represented Interpersonal motivations related to communication or help-seeking. Convergent validity and divergent validity of IMSA scales were supported by expected patterns of correlations with another measure of suicide motivations. In addition, the IMSA scales displayed clinical utility, in which greater endorsement of intrapersonal motivations was associated with greater intent to die, whereas greater endorsement of interpersonal motivations was associated with less lethal intent and greater likelihood of rescue. Findings suggest the IMSA can be of use for both research and clinical purposes when a comprehensive assessment of suicide motivations is desired.