Papers reflecting a series of studies of twins utilising the Maudsley Twin Register, 1932-1999, reflecting the respective impacts of genetics and environment on a range of psychotic disorders, notably schizophrenia. Records include patient files/notes, 1932-1998; patient study profiles arising from tests, questionnaires and comments, 1948-1998; administrative records relating to funding applications to the Medical Record Council, ethical approval, and recruitment of subjects, 1948-1998. Studies include Opposite Sex Twin Study, Kendall Depressives Twin Study, Multiple Psychotic Families Twin Study, Maudsley Adult Twins Study, Anxious Twins Series, Personality Disorder Twin Study, Separated Twin Study, Psychotic Twin Studies, and the Gottesman and Shields series of studies on schizophrenia. The work of Professor Robin M Murray, Dr Adrienne M Reveley, Dr Alison M MacDonald and R Fulrich are also particularly reflected in the files.

Papers relating to the Familial and Environmental Factors in Functional Psychosis Study, 1987, comprising patient files; data from patient interviews; data sheets detailing the patients' symptoms and treatment; project proposal, blank forms and questionnaires used in the study and in-patient medical notes relating to patients with schizophrenia.