Schizophrenia is a symptomatically heterogeneous disorder characterized by the presence of positive and negative symptoms, and variable impairment in community functioning. Given the diversity of symptom presentations and functioning associated with schizophrenia, one of the key challenges facing the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) schizophrenia trial was the selection of efficient assessment measures appropriate to a community-based effectiveness trial. This article describes the rationale for the measurement approach adopted for the trial, provides a brief overview of the selected measures, and describes the process of training assessment raters for a large and geographically dispersed study group.