This book provides an overview of research in the study of household food security in the United States and India. An estimated 85.1 percent of American households were food secure throughout the entire year in 2011, meaning that they had access at all times to enough food for an active, healthy life for all household members. The remaining households (14.9 percent) were food insecure, meaning that the food intake of one or more household members was reduced and their eating patterns were disrupted at times during the year because the household lacked money and other resources for food. Comparatively, this book provides a quantitative assessment of food security using a large household-level expenditure survey conducted by the Government of India during 2004/2005. The analysis tests the impact of several key assumptions required to estimate actual calories consumed from the expenditure data.