Family-based designs are used for a variety of reasons in genetic epidemiology, including the initial estimation of the strength of genetic effects for a disease, genetic linkage analysis by which genetic causes can be sublocalized to chromosomal regions, as well as to perform association studies that are not confounded by ethnic background. This chapter describes some of the approaches that are followed in the initial characterizing of genetic components of disease and family-based designs for association analysis and linkage with genetic markers.