Employment is central to the concept of recovery in severe mental illness. However, common comorbid conditions present significant obstacles to consumers seeking employment and benefiting from vocational rehabilitation. We review research on the effects of three common comorbid conditions on work and response to vocational rehabilitation, including cognitive impairment, substance abuse, and medical conditions, followed by research on vocational rehabilitation. We then present the results of a randomized controlled trial evaluating the effects of adding cognitive remediation to a vocational rehabilitation program compared with vocational rehabilitation alone in 34 consumers with severe mental illness. Consumers who received both cognitive remediation and vocational rehabilitation demonstrated significantly greater improvements on a cognitive battery over 3 months than those who received vocational rehabilitation alone and had better work outcomes over the 2-year follow-up period. Substance abuse was associated with worse employment outcomes, but did not interact with treatment group, whereas medical comorbidity was not related to work outcomes. More research is warranted to evaluate the interactions between substance abuse and medical comorbidity with vocational rehabilitation and cognitive remediation.