Background: It is well-established that the incidence of major depressive disorder is increased in subjects with subthreshold depression. A new research area focuses on the possibilities of preventing the onset of major depressive disorders in subjects with subthreshold depression. An important research question for this research area is which subjects with subthreshold depression will develop a full-blown depressive disorder and which will not. Methods: We selected 154 older subjects with subthreshold depression (CES-D > 16) but no DSM mood disorder from a longitudinal study among a large population based cohort aged between 55 and 85 years in The Netherlands. Of these subjects, 31 (20.1 %) developed a mood disorder (major depression and/or dysthymia) at three-year or six-year follow-up. We examined risk factors and individual symptoms of mood disorder as predictors of onset of mood disorder. Results: Two variables were found to be significant predictors in both bivariate and multivariate analyses: eating problems and sleep problems. The incidence of mood disorders differed strongly for different subpopulations, varying from 9% (for those not having any of the two risk factors) to 57% (for those having both risk factors). Conclusions: It appears to be possible to predict to a certain degree whether a subject with subthreshold depression will develop a mood disorder during the following years.