How personality might contribute to the way people react to illness and personal change has been the subject of speculation for nearly 100 years but precious little empirical research. It is only with prospective longitudinal cohort studies that such issues can be addressed systematically. We will make use of a UK birth cohort (ALSAPC) to examine personality and other dispositional factors, measured during childhood and adolescence to see if these predict or shape the person's insight into later mental illness. In particular we will see if certain attitudes such as whether life is controllable and whether it is good to be consistent make it more difficult for people to accept they have an illness (if it strikes them later as an adult) and to accept treatment.