This report uses the most recently available data from the National Health and Nutrition Examination Survey (NHANES 1999-2004) to provide a comprehensive picture of the diets of Women, Infants, and Children (WIC) participant children--the largest segment of the WIC population. The report examines nutrient intakes, diet quality, and food choices--including consumption of WIC-approved foods. Data are presented for WIC participant children and two groups of nonparticipant children--those who were income-eligible for WIC but did not participate in the program, and higher-income children who were not eligible for the program. The research presented in this report addresses four basic questions about the diets of WIC participant children: Do WIC participants get enough of the right kinds of foods to eat (measured in terms of nutrient intakes and energy sources)? Are WIC children more likely to be overweight than nonparticipants (are they consuming too many calories)? How does the quality of diets consumed by WIC children compare with those of nonparticipant children? And how do food choices differ for WIC participants and nonparticipants (do different food choices help explain differences in diet quality)? A primary conclusion is that the diets of children who participate in the WIC program were generally comparable to the diets of children who do not participate. The prevalence of adequate nutrient intakes is very high for this age group. However, there are specific areas where dietary quality is in need of improvement. Recommendations include reducing children's intakes of saturated and solid fats, sodium, and sweetened beverages, and increasing intakes of dietary fiber. Contents include: (1) Introduction; (2) Usual Daily Intakes of Vitamins, Minerals, and Fiber; (3) Energy Intakes; (4) Meal and Snack Patterns; (5) Food Choices; (6) The Healthy Eating Index-2005 and Sources of MyPyramid Intakes; and (7) Conclusion, including key findings and implications for WIC Nutrition Education. Appended are: (A) Data and Methods; (B) Nutrient Intake Tables; and (C) Other Detailed Tables. (Contains 26 tables and 38 figures.)