Background: This study addresses the question whether personality is a predictor for becoming depressed in late life. We expect that personality traits are significantly associated with the onset of depression, but that the effect of personality is overwhelmed by the effect of health related variables. The second research question concerns whether the strength of this association is affected by the influence of age or age-related deteriorations in the other prognostic factors. We hypothesize to find that a high neuroticism level or low levels of mastery, self-efficacy or self-esteem strengthen the impact of the health-related variables and social situational factors on the onset of depression in late life. Methods: Out of a population-based baseline sample (Longitudinal Aging Study Amsterdam) of 1511 non-depressed elderly respondents (55-85 years at baseline), 255 (17%) developed a clinically relevant level of depressive symptoms during the 6-year follow-up period. Data on the effect of personality on onset were analysed using logistic regression analyses. Results: Both at univariate and multivariate level, the personality traits studied predicted the onset of depression. The effect of neuroticism was more strongly related to onset than health-related and social factors. Results revealed no significant interaction effects between the personality characteristics and age or the other prognostic factors on the association with onset of depression. Discussion: Personality, neuroticism in particular, was found to be a consistent and important predictor of the onset of depressive symptoms in late life, even more important than health-related and situational factors, and aging did not affect the strength of this association.