Klonsky and May (2014) argued that an "ideation-to-action" framework should guide suicide theory, research, and prevention. From this perspective, (a) the development of suicide ideation and (b) the progression from ideation to suicide attempts are distinct processes with distinct explanations. The present article introduces a specific theory of suicide rooted in the ideation-to-action framework: the Three-Step Theory (3ST). First, the theory hypothesizes that suicide ideation results from the combination of pain (usually psychological pain) and hopelessness. Second, among those experiencing both pain and hopelessness, connectedness is a key protective factor against escalating ideation. Third, the theory views the progression from ideation to attempts as facilitated by dispositional, acquired, and practical contributors to the capacity to attempt suicide. To examine the theory, the authors administered self-report measures to 910 U.S. adults utilizing Amazon's Mechanical Turk (oversampling for ideation and attempt histories). Results supported the theory's central tenets. First, an interactive model of pain and hopelessness accounted for substantial variance in suicide ideation. This result replicated in both men and women, and across age groups (i.e., 18-25, 26-35, and 36-70). Also as predicted, connectedness was most protective against ideation in those high on both pain and hopelessness. Finally, dispositional, acquired, and practical aspects of suicide capacity each predicted suicide attempt history over and above current and lifetime suicidal ideation. These initial findings support the 3ST. Implications for suicide prevention and future research are discussed.

Suicidal behavior is a leading cause of death and disability worldwide. Fortunately, recent developments in suicide theory and research promise to meaningfully advance knowledge and prevention. One key development is the ideation-to-action framework, which stipulates that (a) the development of suicidal ideation and (b) the progression from ideation to suicide attempts are distinct phenomena with distinct explanations and predictors. A second key development is a growing body of research distinguishing factors that predict ideation from those that predict suicide attempts. For example, it is becoming clear that depression, hopelessness, most mental disorders, and even impulsivity predict ideation, but these factors struggle to distinguish those who have attempted suicide from those who have only considered suicide. Means restriction is also emerging as a highly effective way to block progression from ideation to attempt. A third key development is the proliferation of theories of suicide that are positioned within the ideation-to-action framework. These include the interpersonal theory, the integrated motivational-volitional model, and the three-step theory. These perspectives can and should inform the next generation of suicide research and prevention.

Most individuals who consider suicide do not make suicide attempts. It is therefore critical to identify which suicide ideators are at greatest risk of acting on their thoughts. However, few seminal theories of suicide address which ideators go on to make attempts. In addition, perhaps surprisingly, most oft-cited risk factors for suicide-such as psychiatric disorders, depression, hopelessness, and even impulsivity-distinguish poorly between those who attempt suicide and those who only consider suicide. This special section of Suicide and Life-Threatening Behavior serves to highlight this knowledge gap and provide new data on differences (and similarities) between suicide attempters and suicide ideators.

Theoretical and empirical literature suggests that nonsuicidal self-injury (NSSI) may represent a particularly important risk factor for suicide. The present study examined the associations of NSSI and established suicide risk factors to attempted suicide in four samples: adolescent psychiatric patients (n = 139), adolescent high school students (n = 426), university undergraduates (n = 1,364), and a random-digit dialing sample of United States adults (n = 438). All samples were administered measures of NSSI, suicide ideation, and suicide attempts; the first three samples were also administered measures of depression, anxiety, impulsivity, and borderline personality disorder (BPD). In all four samples, NSSI exhibited a robust relationship to attempted suicide (median Phi = .36). Only suicide ideation exhibited a stronger relationship to attempted suicide (median Phi = .47), whereas associations were smaller for BPD (median rpb = .29), depression (median rpb = .24), anxiety (median rpb = .16), and impulsivity (median rpb = .11). When these known suicide risk factors and NSSI were simultaneously entered into logistic regression analyses, only NSSI and suicide ideation maintained significant associations with attempted suicide. Results suggest that NSSI is an especially important risk factor for suicide. Findings are interpreted in the context of Joiner's interpersonal-psychological theory of suicide; specifically, NSSI may be a uniquely important risk factor for suicide because its presence is associated with both increased desire and capability for suicide.

Most suicide ideators do not attempt suicide. Thus, it is useful to understand what differentiates attempters from ideators. We meta‐analyzed 27 studies comparing sociodemographic and clinical variables between attempters and ideators. When comparing ideators to nonsuicidal individuals, there were several large effects. For example, depression and PTSD were markedly elevated among ideators (d = .85–.90). In contrast, when comparing attempters to ideators, all 12 variables had negligible to moderate effects. Specifically, depression, alcohol use disorders, hopelessness, gender, race, marital status, and education all were similar in attempters and ideators (d = −.05 to .31). Anxiety disorders, PTSD, drug use disorders, and sexual abuse history were moderately elevated in attempters compared to ideators (d = .48–.52). Implications for theory and practice are discussed.