This work for this thesis was conducted over an 11 year period (1983 to 1994). It is this a little different from the usual time course for such an undertaking. With the exception of the first study presented in Chapter 2 which was undertaken in 1983/4 as a Senior Registrar in Old Age Psychiatry, the research to be described was conducted while I was a National Health Service consultant. The central theme, namely the prognosis of depression in later life, has been developed over this period, along with some related themes such as the role of organic cerebral pathology and organic risk factors. The resulting Thesis thus incorporates five separate studies. The first and perhaps pivotal one was a naturalistic retrospective outcome study; next are two studies of delusional depression, one retrospective and the other prospective; then a prospective study of cerebral organic disease in relation to outcome; and, lastly, the role of vascular risk factors in late-onset depression. For the first outcome study and the retrospective one of delusional depression, the study groups comprised patients from South Manchester Old Age Psychiatry Services. For the prospective study of delusional depression and of vascular risk factors, they were patients solely under my care. For the study of cerebral organic factors they were patients of the Central Manchester Old Age Psychiatry Service. Ethical approval was obtained for each of the studies in the appropriate clinical Districts. Rather than producing a thesis of unconnected studies, it is hoped that this approach demonstrates the role of the consultant in undertaking research in clinically relevant areas and, because of the longer term perspective which a consultant can take, being able to pose a series of inter-related questions, each developing a theme from an earlier study.