The effect of three sources of protein: soy, dairy, and meat protein, and two levels of calcium on zinc, iron, copper, calcium, and magnesium retention in young adult men was determined in a 30-day metabolic balance study. The study was divided into a twenty-day baseline period, a thirty day controlled feeding period from which all the balance data was collected, and a twenty day follow-up period. During the controlled feeding period, twenty-four subjects were randomly assigned to one of three dietary treatment groups which differed in respect to protein source. The dairy treatment group was fed a diet in which 70% of the dietary protein was derived from dairy products; the soy treatment group was fed a diet in which 67% of the dietary protein was derived from soy products; and the meat treatment group was given a diet in which 70% of the dietary protein was provided by animal meat products. To test the effect of calcium level on mineral retention, the controlled feeding period was divided into two periods: Period I, in which the subjects consumed moderate levels of calcium (mean= 1206.77 + 193.29 mg/day) and Period II, in which the subjects consumed high levels of calcium (mean 2134.51 + 164.63 mg/day). / Master of Science