This study aimed to compare perceived stress, resilience, and suicidal ideation among single-parent and two-parent middle school students. The research was applied in nature and employed a descriptive, causal-comparative, and cross-sectional design. The statistical population included all female first-grade middle school students in Karaj City during the 2023–2024 academic year. Based on Delavar's (2017) recommendation of a minimum of 30 participants per group in causal-comparative studies and accounting for potential attrition, a sample size of 50 students per group was selected, totaling 300 students across five groups (two-parent = 100; single-parent due to divorce or death = 200). Sampling was conducted using convenience and purposive methods. Research instruments included the Perceived Stress Scale (Cohen et al., 1983), the Child and Youth Resilience Measure (Ungar & Liebenberg, 2009), and the Suicidal Ideation Questionnaire (Keith, 1984). Data were analyzed using independent samples t-test in SPSS-27. The findings revealed significant differences between single-parent and two-parent groups across all three variables (p < 0.05). The mean perceived stress was higher in single-parent students (M = 46.52) than in two-parent students (M = 41.10); resilience was lower in single-parent students (M = 110.37) compared to two-parent students (M = 114.85); and suicidal ideation was higher in single-parent students (M = 8.61) than in two-parent students (M = 6.60). Given the cross-sectional nature of the study, these findings indicate associations between family structure and mental health indicators; however, causal relationships cannot be inferred. Designing and implementing psychological and counseling interventions for single-parent students is essential to prevent mental health risks and enhance coping capacities.