An interdisciplinary conceptual framework of food security is presented that identifies determinants at the macro-socioeconomic, regional-local, and household levels. Food insecurity is described as having consequences for health and well-being that may or may not be expressed in the form of physical-biological consequences such as underweight or nutritional deficiencies. The implications of this perspective for measurement of food security are addressed. A comparative review of indicators commonly used to assess food security is presented, with special focus on the Brazilian Food Insecurity Scale, which was included in the 2004 National Household Survey (PNAD). The history of the development of the scale in the U.S. and its validation in Brazil are described. Characterized as a direct measure of household food insecurity, this psychometric scale can be used together with indicators and measurement instruments from diverse fields to broaden understanding of this complex phenomenon.