Objective A prior 4-week, proof-of-concept study suggested that adjunctive therapy with armodafinil 200mg/day decreases negative symptoms in patients with clinically stable schizophrenia. This study investigated the efficacy and tolerability of adjunctive armodafinil for treatment of negative symptoms in adults with schizophrenia receiving antipsychotic medications. Methods This parallel-group, 24-week study enrolled adults with schizophrenia who were receiving oral olanzapine, risperidone, or paliperidone for ≥6weeks, and had a Positive and Negative Syndrome Scale (PANSS) negative symptom subscale score of ≥15. Patients received one of 3 doses of once-daily armodafinil (150mg, 200mg, or 250mg) or placebo. The primary efficacy measure was the change from baseline to final visit in the PANSS negative symptom subscale score. Secondary measures included the PANSS total score, Clinical Global Impression of Severity, Personal and Social Performance Scale, and CNSVitalSigns cognitive battery. Results Of 285 randomized patients, 213 received armodafinil and 72 received placebo. The mean (SD) changes in PANSS negative symptom subscale score were −1.9 (3.8) for armodafinil 150mg (n=70), –2.3 (3.6) for armodafinil 200mg (n=69), –2.0 (3.3) for armodafinil 250mg (n=71), and −2.2 (4.1) for placebo (n=70) (p≥0.70 for each armodafinil group versus placebo). Secondary measures were generally not different between groups. Armodafinil was generally well tolerated, without worsening positive symptoms. Conclusions This study found no benefit of adjunctive armodafinil versus placebo for negative symptoms in patients with schizophrenia receiving treatment with olanzapine, risperidone, or paliperidone. Armodafinil was generally well tolerated in these patients.