The authors used structural equation modeling to test the mediational role of affect regulation on attachment and deliberate self-harm in 216 undergraduates. Results suggest that affect regulation mediates the relationship between attachment and deliberate self-harm, providing support for the theoretical importance of attachment and affect regulation in the etiology of self-harm behaviors. Accordingly, attachment styles should be considered when providing clinical assistance to college students in an effort to improve affect regulation and to treat deliberate self-harm.