This volume contains the edited transcript of the second Totts Gap Colloquium, held at Totts Gap, Pennsylvania, May 29-31, 1975. The objective of the Colloquium was to bring into focus what is known of pathogenic mechanisms of schizophrenic manifestations. One hope was to differentiate among syndromes that share the fea~ tures of schizophrenia, disorganization of thought and talk, inap- propriateness of affect, circumstantiality, withdrawal from social interaction, paranoid ideation, hallucinations, delusions, catelepsy, catatonic excitement or mutism, etc. What is known of the neural and chemical processes capable of inducing such aberrations was discussed with an attempt to reconcile disparate findings and in- terpretations, to synthesize current evidence and to point up cru- cial areas of ignorance that need exploration. The program was designed to further the objectives of the Multidisciplinary Research Program in Mental Health, of the University of Texas Medical Branch and to supplement their efforts with a well focused look at the schizophrenic process. Accordingly, Dr. Allan Goldstein, Professor of Biochemistry and Acting Director of the Multidisciplinary Re- search Program in Mental Health; Dr. Bernard Haber, Associate Pro- fessor of Biochemistry and Member of the Marine Biomedical Institute; and Dr. Geraldine Cohen, Assistant Professor, Department of Human Biological Chemistry and Genetics, joined in discussion with the Colloquium participants who were as follows: Dr. Mark D. Altschule, Clinical Professor, Harvard Medical School. Dr. Llewellyn B. Bigelow, Director of ~ental Health Research, St. Elizabeth's Hospital. Dr. Eugene L. Bliss, Professor and Chairman of Psychiatry, University of Utah.