Although the majority of adults with learning disabilities (LD) or attention-deficit/hyperactivity disorder (ADHD) do not have serious psychological disorders, they may have an increased risk of experiencing some psychological or social problems and substance abuse (Cosden, 2001; Kollins, 2008; Morrison & Cosden, 1997; Ramsay & Rostain, 2008; Ratey, Hallowell, & Miller, 1997; Sharps, Price-Sharps, Day, Viggegas, & Nunes, 2004). Current information suggests that these adults may also have less success than those without these disorders in various psychological interventions, such as substance abuse treatment (Carroll & Rounsaville, 1993; Cosden & Greenwell, 2006; Levin et al., 2004; Yu, Buka, Fitzmaurice, & McCormick, 2006). However, information regarding factors that may contribute to this is limited. The present study used a sample of 213 participants (29% self-identified as having LD and/or ADHD) who were surveyed when they exited one of two court-monitored substance abuse treatment programs. The effect of having LD/ADHD on the development of substance use disorder (SUD) and on substance abuse treatment outcomes was examined. Results indicate that participants with LD/ADHD were less likely to complete treatment and experienced more risk factors, such as history of experiencing abuse and more days in the past month with psychological problems than did adults with no cognitive disabilities (NCD). For both groups (LD/ADHD and NCD) the same factors predicted treatment failure. These predictors included male gender, higher number of days in the past month with psychological problems, and having one or more close friends who used substances. Although disability status does not appear to be a significant predictor of treatment outcome once the other factors are accounted for, it may serve as a proxy variable to help identify at risk participants if the other predictors are unknown, because participants with LD/ADHD experienced more of two of these three risk factors (i.e., more days in the past month with psychological problems and more likely to be male). Clinical implications regarding needs of participants with LD/ADHD in substance abuse treatment and directions for future research are discussed.