The study evaluates the relationship between BMD and coronary artery and aortic calcification, measured by electron beam computed tomography, in 700 members of a large Amish pedigree already participating in the Amish Family Osteoporosis Study (AFOS). By focusing on families, the investigators hope to tease out the respective contributions of genetic and non-genetic factors to this clustering of traits. The AFOS was initiated in 1997 to identify genes influencing susceptibility to osteoporosis in families ascertained for fracture risk. Through NIH funding available to the AFOS parent study, the investigators will genotype 391 highly polymorphic short tandem repeat (STR) markers spaced at approximately 10 cM intervals and perform a genome-wide scan to detect quantitative trait loci (QTLs) associated with variation in bone marrow density and related traits. The Old Order Amish are ideal for the studies since they are a closed founder population who are relatively genetically homogeneous, have very large family sizes, and well-documented genealogies. The study uses the available measures of bone marrow density, related traits, and genotypes in the AFOS along with the newly collected measures of vascular calcification.