This study examined the link between executive function and functional outcome in schizophrenia to identify useful psychological intervention targets and explore how executive function changes affect social functioning and symptoms. Participants from two randomized controlled trials (n = 63) with poor social functioning, positive and negative symptoms, and cognitive impairment completed seven measures of executive function. Three cognitive factors were extracted: verbal working memory, response inhibition speed, and stimulus-driven responding. Participants received individual cognitive remediation therapy (CRT) (n = 18), a control therapy (occupational therapy activities) (n = 14), or treatment as usual (n = 19). Only the CRT group improved on verbal working memory. No group improved on the other factors. Although verbal working memory was significantly associated with social functioning and symptom severity 3 months after baseline, change in this factor did not predict change in either functional outcome. There was a significant interaction between group and the stimulus-driven responding factor, and for the CRT group only, a change to a more externally focused responding style was associated with reduced social problems and symptoms. Regardless of treatment type, increased response inhibition speed was associated with reduced negative symptoms. Stimulus-driven responding and response inhibition speed may therefore make useful targets for intervention.