Purpose: The aim of this study was to examine the longitudinal association between educational level and frailty prevalence in older adults and to investigate the role of material, biomedical, behavioral, social, and mental factors in explaining this association. Methods: Data over a period of 13years were used from the Longitudinal Aging Study Amsterdam. The study sample consisted of older adults aged 65 years and above at baseline (n=1205). Frailty was assessed using Fried's frailty criteria. A relative index of inequality was calculated for the level of education. Longitudinal logistic regression analyses based on multilevel modeling were performed. Results: Older adults with a low educational level had higher odds of being frail compared with those with a high educational level (relative index of inequality odds ratio, 2.94; 95% confidence interval, 1.84-4.71). These differences persisted during 13years of follow-up. Adjustment for all explanatory factors reduced the effect of educational level on frailty by 76%. Income, self-efficacy, cognitive impairment, obesity, and number of chronic diseases had the largest individual contribution in reducing the effect. Social factors had no substantial contribution. Conclusions: Our findings highlight the need for a multidimensional approach in developing interventions aimed at reducing frailty, especially in lower educated groups. © 2014 Elsevier Inc.