Internet-delivered Skills Training in Affective and Interpersonal Regulation (i-STAIR) will be an effective intervention for preventing depression among those with adverse childhood experiences and subsyndromal depression. In contrast to the control group (i.e., individuals who received online general psychoeducation), we hypothesize that participants who receive i-STAIR will experience a significant reduction of depressive/PTSD symptoms and emotion dysregulation, as well as experience significant positive increases in interpersonal skills and perceptions of social support at post-intervention.