Exposure to traumas early in life has been found to have a range of negative health effects later in adulthood, including a higher risk for suicidal behavior. Using data from the Waves I (1994/95) and IV (2008) of the National Longitudinal Study of Adolescent to Adult Health (N = 14,385; 49.35% female; Mage in Wave IV = 29), this study examines the effects of exposure to three different types of early life traumas—emotional abuse, physical abuse, and sexual abuse before the age of 18—on adult suicidal ideation. Guided by the stress process model incorporated with a life-course perspective, potential mediating roles of psychological distress, subjective powerlessness, and perceived social rejection were also investigated. A series of regression and Karlson-Holm-Breen (KHB) mediation analyses were performed using Stata 14 to assess the total, direct, and indirect effects. All three early life trauma measures were found to be significantly and independently associated with a higher risk of suicidal ideation in adulthood. A substantive portion (between 30 and 50%) of the effects was mediated by psychological distress (i.e., depression and anxiety), subjective powerlessness, and perceived social rejection. The general policy implications of this study include evaluating suicidal individuals for prior childhood abuse experiences and assessing abuse survivors for suicidality.