AbstractExamined the relationship between overinclusion and manic symptomatology in 46 schizophrenics using a reliable, structured research interview to assess symptomatology, and research diagnostic criteria to identify a subgroup of schizophrenics with concurrent manic syndromes. Of the three measures of overinclusive thinking employed in the study, only one significantly differentiated the schizoaffective and schizophrenic groups. Similarly, only one overinclusion test was correlated with the number of manic symptoms that patients exhibited. Finally, overinclusive and nonoverinclusive schizophrenics did not differ on specific manic signs and symptoms. Overinclusion also was unrelated to patients' overall levels of schizophrenic symptomatology. These results indicate that overinclusive thinking is related only weakly to manic symptomatology in schizophrenics, which suggests that this factor cannot account fully for the prognostic and cognitive benefits associated with overinclusion.