The purpose of this study is to determine whether adding calcium to the diet prevents bone loss in men age 65 years and older. Healthy ambulatory men, 65+ years, with a daily calcium intake of <1000mg/day and normal femoral bone mineral density (range Z score between -0.5 and +1.0) were recruited for a 2-year double-masked, placebo-controlled study. Thus far, 84 men have been screened with 41 qualifying for the study. Currently, negotiations with Bethesda Naval Hospital are on-going to start a second study site. Recruitment of healthy elderly men has been slower than expected. As a result, further expansion of this study to other sites is under investigation.