Objective: Neuropsychological deficits are present in schizophrenia and bipolar disorder. These deficits are associated with a number of disorder related variables such as negative symptoms. Because profile of negative symptoms and neuropsychological deficits vary across individuals, linear approaches to examining these relationships may fail to capture profile pattern differences. The current study uses cluster analysis to examine negative symptom profile differences in serious mental illness to investigate whether profile differences were associated with unique patterns of cognitive deficits and functional outcomes. Method: The sample consisted of 96 adults with bipolar disorder (age = 38.89, education = 14.01) or schizophrenia (age = 40.76, education = 12.32). Three-, four-, and five-cluster solutions of negative symptom ratings (SANS) were examined using cluster analysis (Ward's method with squared Euclidian distance). The three-cluster solution was selected as optimal and comparisons were then made between clusters for cognitive abilities (WAIS-III) and functional outcomes (UPSA). Results: Clusters were differentiated by profile of negative symptoms. Differences were observed between clusters on cognitive and functional variables, with the cluster having the most severe negative symptoms exhibiting the greatest impairment and those with the least severe negative symptoms exhibiting the best performance. Differences on clinical variables were also apparent among the clusters. Conclusion: Results suggest that there are pattern differences in negative symptoms for individuals with serious mental illness and these differences are associated with distinct cognitive and functional deficits. Profile analysis of negative symptoms may therefore be useful in identifying those individuals as particular risk for cognitive and functional deficits.