This population-based, case-control study in King County,Washington examined associations of energy, fat, vitamin D, and calcium with risk of prostate cancer in 605 incident cases (ages 40-64 years) identified from the Seattle-Puget Sound Surveillance Epidemiology and End Results registry and 592 controls recruited from the same underlying population using random-digit telephone sampling. Self-administered food frequency questionnaires were used to assess diet over the 3-5-year period before diagnosis or interview date. Total energy was associated with increased risk for both local and regional/distant stage disease. The adjusted odds ratios [95% confidence intervals (CIs)] contrasting highest to lowest quintile of energy intake were 2.15 (95% CI, 1.35-3.43) for local and 1.96 (95% CI, 1.08-3.56) for regional/distant disease. Fat was associated with regional/distant disease only. Adjusted odds ratios comparing the highest to lowest quintiles of percentage energy from total, saturated, and monounsaturated fats were 2.01 (1.03-3.92), 1.82 (0.93-3.56), and 2.00 (1.03-3.87), respectively. For calcium, adjusted odds ratios contrasting the highest to lowest quartiles were 1.07 (0.63-1.84) for local and 2.12 (1.02-4.38) for regional/distant disease. There were no associations of vitamin D, total polyunsaturated fatty acids, or the highly unsaturated, long-chain eicosapentainoic and docosahexaenoic fatty acids with prostate cancer risk. These results suggest that high energy intake is a risk factor for both localized and nonlocalized prostate cancer, whereas dietary fat and calcium increase the risk of regional/distant disease only. These results are consistent with general dietary guidelines to moderate consumption of total energy and fat, and they motivate further research to consider the potential benefits and risks of high calcium intake.