The work of Valerie Sinason, a child psychotherapist and adult psychoanalyst, has been of major importance in the field of learning disability. Sinason's clinical and theoretical contributions to psychotherapy in this area of extreme psychopathology are examined in detail and an assessment is made of the extent to which these contributions represent major advances in the understanding and treatment of mentally handicapped patients. A detailed examination of the clinical and theoretical insights that emerged from her work with learning disabled patients shows the major impact she has had in promoting the use of psychoanalytic psychotherapy with such patients.