Adverse childhood experiences (ACEs) are significant developmental risk factors that, in interaction with individual, familial, and social conditions, may increase adolescents’ vulnerability to delinquency. This study examined the relationship between adverse childhood experiences and theft offending and compared these experiences among adolescents who had committed theft and non-delinquent adolescents in Alborz Province, Iran. This quantitative study used a causal-comparative (ex post facto), cross-sectional design. The sample included 62 adolescents aged 15–18 who had committed theft and resided in the Juvenile Correction and Rehabilitation Center of Alborz Province, and 742 non-delinquent adolescents (412 boys and 330 girls). Childhood trauma was assessed using the Childhood Trauma Questionnaire (CTQ), supplemented by questions on violence against mothers and family dysfunction. Data were analyzed using the non-parametric Mann–Whitney U test. The findings showed that total childhood trauma scores and all dimensions were significantly higher among adolescents who had committed theft than among non-delinquent adolescents (p < .001). The largest difference concerned physical neglect, followed by other forms of maltreatment and neglect. The former group also reported more frequent exposure to violence against their mothers, parental divorce, parental substance abuse, and parental incarceration. These findings suggest that adolescent theft cannot be explained solely by a single risk factor or economic motivation. Rather, cumulative adverse childhood experiences may increase vulnerability to delinquency by undermining parental care and supervision, emotional bonds, and self-regulatory processes. Preventing adolescent theft therefore requires early identification of children exposed to adversity and stronger family-centered interventions and social support.