Within the Dimensional Model of Adversity and Psychopathology, extant research shows that exposure to threat—including emotional, physical, and sexual abuse—is linked to psychopathology among adolescents; problems with emotion regulation may, at least in part, explain this association. Both theoretical and empirical work also suggests that emotion regulation difficulties—particularly access to emotion regulation strategies—may mediate the relation between threat and self-injurious thoughts and behavior, though no studies to date have explicitly tested this model. The current study tested relations between threat, limited access to emotion regulation strategies, and self-injurious thoughts and behaviors among high-risk youth across an 18-month follow-up. The sample consisted of 180 adolescents (Mage = 14.89; SD = 1.35; ages 12–17; 71.7% female; 78.9% White; 55.0% heterosexual) recruited from an inpatient psychiatric unit. Threat was assessed at baseline using the abuse subscales from Childhood Trauma Questionnaire. Access to emotion regulation strategies was assessed using the Difficulties in Emotion Regulation Scale at baseline, 6-, and 12-months. Presence (versus absence) of non-suicidal self-injury and suicidal ideation severity were assessed at baseline, 12-, and 18-months using the Self-Injurious Thoughts and Behaviors Interview and the Suicidal Ideation Questionnaire-JR, respectively. After accounting for baseline levels of the mediator, outcome, and depressive symptoms, structural equation models supported the role of 12-month access to emotion regulation strategies as a mediator between baseline threat and 18-month suicidal ideation and non-suicidal self-injury. Treatment aimed at bolstering access to emotion regulation strategies may help reduce suicide risk among youth who have experienced childhood abuse.