Persons with serious mental illness (SMI) struggle with work functioning even with the assistance of vocational services. The current study sought to address this problem by examining a cognitive-behavioral therapy to augment vocational services. Fifty-two adults with SMI receiving vocational services participated in a pre-post feasibility trial of the Cognitive Behavior Therapy for Work Success (CBTw) intervention. CBTw is a 12-week manualized intervention that addresses cognitive and behavioral factors that impact work functioning. Competitive work outcomes were assessed in the 12 weeks preceding baseline and after the intervention. The results demonstrate strong session attendance and a low attrition rate. There were also significant improvements in work outcomes. Specifically, among participants unemployed at baseline, 50.0% attained work during follow-up. These findings provide preliminary evidence that CBTw may be a feasible intervention to augment vocational services; further controlled research should examine its benefit to work outcomes in people with SMI.