It has been established in the literature that aggressive behaviors in individuals with intellectual disabilities (ID) represents a high percentage of referrals to mental health services (Davidson, Cain, Sloane-Reeves, Speybroech, Segel, et al., 1994). The results of several studies conducted with children with ID and aggressive behaviors indicate that, overall, aggressive individuals are less accurate in identifying other peoples' intentions, have a harder time when interpreting ambiguous and benign situations, and tend to generate higher numbers of aggressive solutions (Basquill, Nezu, Nezu, & Klein, 2004; Leffert, & Siperstein, 1996; Pert, Jahoda, & Squire, 1999). A connection between how individuals appraise social situations and the behaviors they display has been suggested (Baker, & Bramston, 1997). However, studies conducted with adults with ID and aggressive behaviors have yielded mixed results. Intervention approaches that aim to clarify those links and to change faulty beliefs seem to be on target. However, to date, evidence of the effectiveness of such approaches is inconclusive. The current study compared the relative effectiveness of a cognitive re-appraisal approach and a problem-solving approach to improve social cognition in adults with ID who exhibit aggressive behavior. The dependent variables of primary interest were the participants' ability to understand intentionality, generate assertive/effective problem solving strategies, and regulate anger. Thirty six individuals with ID and aggressive behavior participated in this study. Participants were randomly assigned to one of three treatment conditions (cognitive re-appraisal treatment group, problem-solving treatment group, and control group). A group experimental design was utilized. Overall, results from the study suggested that individuals with ID and aggressive behaviors can benefit from social-cognitive approaches. Individuals who participated in the cognitive re-appraisal intervention approach, at posttest, demonstrated a higher incidence of assertive responses in comparison to a control group. No significant differences were observed between the cognitive re-appraisal group and the problem solving group. A significant difference was observed on the aggression questionnaire B (filled by participants) on the indirect aggression scale. No significant differences were observed among the groups with respect to the participants' ability to identify other people's intent. Further research with adults with ID and aggressive behaviors is needed to clarify the effectiveness of socio-cognitive approaches. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]