Food habits formed under particular social and economic conditions, and entirely adequate to those conditions, may be carried by individuals and groups into other settings where they may be unsuitable and even harmful to health. Human behaviour as it relates to food embraces a complex of culinary activities and patterns of consumption resulting from the interaction of ecological, economic, technological, and social factors. This chapter deals with the cultural definition and classification of foods, traditional beliefs and practices as they affect nutrition and health. It also presents the symbolic roles of food that contribute to the integration of social and political units, of nations, communities, and families. Food habits are both changeable and conservative, as they are based on deeply rooted cultural traditions. In suggesting alternatives to existing practices, one must carefully consider, in advance, the costs involved and the means of attaining the desired change.