Objective: Describe the study design, data collection methods, 24-hour dietary recall protocol, and sample characteristics of the Feeding Infants and Toddlers Study (FITS) 2008. Design: A cross-sectional study designed to obtain information on the diets and feeding patterns of US infants, toddlers, and preschoolers ages birth to 47 months. Telephone interviews with parents and caregivers were conducted from June 2008 through January 2009 and included a household interview to recruit the household and collect information on household and child demographics and nutrition-related characteristics, and a dietary interview, including a 24-hour dietary recall collected using the 2008 Nutrition Data System for Research. A second dietary recall was collected on a random subsample to estimate usual nutrient intake distributions. Data collection instruments were built on those used in FITS 2002, with expanded survey content to address emerging issues in childhood nutrition and obesity. The dietary protocol was improved to increase reporting accuracy on portion sizes, and a bridging study was conducted to test effects of the changes in the food model booklet and protocol since FITS 2002 (n=240 cases aged 4 to 23 months). Subjects: A national random sample of 3,273 infants, toddlers, and preschoolers from birth up to age 4 years, with 2 days of dietary intake data for 701 cases. Results: Among sampled households with an age-eligible child, the response rate was 60% for the recruitment interview. Of recruited households, the response rate for the dietary interview was 78%. Conclusions: The FITS 2008 provides rigorous, well-tested methods and survey questions for nutrition researchers to use in other dietary studies of young children. FITS 2008 findings on the food and nutrient intakes of US children from birth up to age 4 years can inform dietetics practitioners, pediatric health practitioners, and policymakers about the dietary issues of young children.