Caroline González-Vega is a Ph.D. candidate in the Stein Monogastric Nutrition Lab. She describes an experiment to determine the effect of the level of calcium and the level of phytate in the digestibility of calcium in inorganic (calcium carbonate) and organic (Vistacal) calcium sources, and the site in the gastrointestinal tract where calcium is absorbed for the two sources. Adapted from a presentation at the 2013 ASAS Midwestern Section meeting, Des Moines, IA, March 11-13.