A total of 260 process schizophrenics were studied to determine the presence of clinical differences supporting the classification of hebephrenic and paranoid subgroups. Hebephrenics, it would appear, have an earlier age of onset, inappropriate or flat affect, and formal thought disorder; paranoids are primarily distinguished by a later age of onset, the presence of well-organized delusions or hallucinations, and the absence of affective changes. In comparison, paranoids tended toward a more favorable outcome, and less familial schizophrenia. Diagnosis of subtypes by computer, based on clinical differences within the process group, yielded a high rate of concordance with clinician subtyping. Based on these findings and currently available literature, a comparative summary of the clinical differences between these subtypes is presented, and criteria for selecting homogeneous subtypes for further research are proposed.