OBJECTIVE: Accumulating evidence suggests that energy-dense foods predispose to obesity and that such foods may also be associated with an increased risk of type 2 diabetes, but there is limited evidence. Our aim was to investigate whether there is an independent association between dietary energy density and incidence of diabetes. RESEARCH DESIGN AND METHODS: The European Prospective Investigation of Cancer (EPIC)-Norfolk Cohort Study was a population-based prospective study of individuals aged 40-79 years at baseline. We calculated energy density for overall diet (all solids and drinks) using food frequency questionnaires. During 12 years of follow-up, we documented 725 new-onset cases of diabetes among 21,919 participants without diabetes, cancer, or cardiovascular disease at baseline. RESULTS: Baseline energy density (adjusted for age, sex, and baseline BMI) was higher in those who developed type 2 diabetes (mean 3.08 kJ/g [95% CI 3.03-3.13]) than in those who remained nondiabetic (3.01 kJ/g [3.00-3.02]) (P = 0.012). Energy density was positively associated with incident diabetes (odds ratio 1.21 per unit increase [95% CI 1.06-1.38]) adjusted for known risk factors. There was a 60% higher risk of diabetes (1.60 [1.19-2.16]) in the highest quintile of energy density (range 3.55-7.97 kJ/g) compared with the lowest quintile (1.04-2.43 kJ/g) in adjusted analysis. CONCLUSIONS: This is the first large population-based prospective study to report that an energy-dense diet may be associated with increased risk of development of diabetes, independent of baseline obesity. The potential public health impact of a low-energy-dense diet on reducing the risk of diabetes deserves further study.