Physical anthropologists have long studied the density of human bones as a reflection of activity and other variables (references in Galloway et al. 1997; Willey et al. 1997), but seldom have they considered it as an intrinsic property of bones that has a significant mediating influence on a variety of taphonomic processes. Thus, the great majority of the literature on bone density as a taphonomically and forensically significant variable concerns nonhuman animal bones. In this chapter, I first briefly review the history of considerations of bone density in taphonomic contexts. Then, I turn to definitions of density as a generic property; this is necessary, because several different properties that more or less closely approximate the density of bone have been measured, but all have been called “density.” Part of the reason that different properties have been measured is revealed by a consideration of how density has been measured in ungulate and other skeletons. Historical review of the techniques used to measure density reveals strengths and weaknesses of the several techniques, provides guidance about how density might be measured in the future, and underscores why certain density values for human skeletal parts are better than others for taphonomic/forensic purposes. Subsequent to the historical review, I turn briefly to how to quantify bone frequencies in order to determine if some skeletal parts have survived attritional processes better than other parts. This leads to a consideration of how past researchers have analytically detected density-mediated attrition in particular collections. Then I present data on the density of human bones and work through examples of analytical techniques using real data. The discussion is concluded with a few thoughts on the future.