Suicidal behavior is a major problem worldwide and, at the same time, has received relatively little empirical attention. This relative lack of empirical attention may be due in part to a relative absence of theory development regarding suicidal behavior. The current article presents the interpersonal theory of suicidal behavior. We propose that the most dangerous form of suicidal desire is caused by the simultaneous presence of two interpersonal constructs-thwarted belongingness and perceived burdensomeness (and hopelessness about these states)-and further that the capability to engage in suicidal behavior is separate from the desire to engage in suicidal behavior. According to the theory, the capability for suicidal behavior emerges, via habituation and opponent processes, in response to repeated exposure to physically painful and/or fear-inducing experiences. In the current article, the theory's hypotheses are more precisely delineated than in previous presentations (Joiner, 2005), with the aim of inviting scientific inquiry and potential falsification of the theory's hypotheses.

The present study examined the psychometric properties and construct validity of scores derived from the Interpersonal Needs Questionnaire (INQ) using latent variable modeling with 5 independent samples varying in age and level of psychopathology. The INQ was derived from the interpersonal theory of suicide and was developed to measure thwarted belongingness and perceived burdensomeness-both proximal causes of desire for suicide. Results support that thwarted belongingness and perceived burdensomeness are distinct but related constructs and that they can be reliably measured. Further, multiple-group analyses were consistent with invariance for young versus older adults and nonclinical versus clinical populations, thereby supporting the relevance of these constructs to diverse populations. Finally, both constructs demonstrated convergent associations with related interpersonal constructs-including loneliness and social support for belongingness and social worth and death ideation for burdensomeness--as well as prospective associations with suicidal ideation.

The Interpersonal Theory of Suicide proposes that suicidal behavior is so frightening that in order for an individual to engage in suicidal behavior, desire for suicide must be accompanied by the capability to do so. The capability for suicide is characterized by both a sense of fearlessness about death and elevated physiological pain tolerance. The primary aim of the current project was to reevaluate and revise the Acquired Capability for Suicide Scale (ACSS; Van Orden, Witte, Gordon, Bender, & Joiner, 2008) and offer a revision to the scale. Expert review of the scale items resulted in retaining 7 items assessing fearlessness about death. The recommendation is made to refer to the revised scale as the ACSS-Fearlessness About Death (ACSS-FAD) to reflect its content more specifically. A model with the 7 retained items provided good fit to the data across 3 independent samples of young adults. Multiple-group analyses examining measurement invariance across men and women found that the latent structure of the scale is comparable across gender. Data are also presented demonstrating convergent and discriminant validity for the scale in young adults and an inpatient psychiatric sample. Findings support the viability of the ACSS-FAD, indicating the scale has a replicable factor structure that generalizes across males and females and is substantively related to the construct of fearlessness about death. Taken together, the present work extends knowledge of the psychometrics of the ACSS-FAD in particular and the nature of fearlessness about death in general.