Background: Suicide, defined as the intentional act of self-inflicted death, constitutes a significant global public health burden. Every year, over 700,000 individuals worldwide die by suicide. Studies in Iran have reported an alarming prevalence of suicidal behavior among students, with estimates of suicide attempts ranging from 1.8% to 3.5%, and suicidal ideation rates fluctuating between 6.2% and 42.7%. This complex phenomenon is influenced by a wide array of factors. A major challenge to effective suicide prevention strategies is the limited understanding of the mechanisms that lead from suicidal ideation to actual suicide attempts. Objectives: This study aimed to investigate the relationships between suicidal ideation, suicidal behaviors, and the constructs of the three-step theory within a student population. Methods: A cross-sectional design was employed, with convenience sampling enrolling 260 students from Zanjan University of Medical Sciences. Students consented to participate and completed various questionnaires, including the Beck Suicide Ideation Scale (BSSI), the Inventory of Motivations for Suicide Attempts (IMSA), the Suicidal Behaviors Questionnaire-Revised (SBQ-R), the Symptom Checklist-25 (SCL-25), the Acquired Capability for Suicide Scale (ACSS), and a single-item suicide attempt question. The participants ranged in age from 18 to 52 years (mean: 23.62, standard deviation: 5.48), with 75% of the sample being female, and 85% single. Data analysis was conducted using SPSS 24 and AMOS 24 software. Results: Correlation analysis revealed that psychic pain, hopelessness, and low belongingness were significantly and directly correlated with both suicidal ideations and behaviors (all P-values < 0.05). Structural equation modeling results demonstrated that the combination of pain and hopelessness directly predicted suicidal ideation (beta = 0.318, P < 0.001) and low belongingness (beta = 0.867, P < 0.001). These factors indirectly predicted suicidal behavior through suicidal ideation, capability for suicide, and low belongingness (beta = 0.406, P < 0.001). Additionally, suicidal ideation was a strong direct predictor of suicidal behavior (beta = 0.556, P < 0.001), and low belongingness directly predicted suicidal behaviors (beta = 0.226, P < 0.001). However, the capability for suicide did not statistically predict suicidal behavior within this student sample. 00Conclusions: The findings support the validity of the three-step theory in a student population. Pain, hopelessness, and low belongingness were significant predictors of suicidal ideation and attempts among students, while the capability for suicide did not predict suicidal behavior in this context. These results provide a novel perspective by confirming the applicability of the three-step theory in a non-clinical student population, offering valuable insights into the interrelations of the model's key components.
