We have randomized 193 JRA patients equally into two treatment groups (active and placebo). The active treatment group is taking, in a single daily dose, two 500 mg tablets of elemental Ca as CaC03 (calcium carbonate) and one multivitamin tablet containing 400 IU vitamin D. The placebo treatment group is taking, in a single daily dose, two placebo tablets (matched on size, appearance, and taste) containing 0 mg elemental Ca and one multivitamin tablet containing 400 IU vitamin D. We do all patient evaluations in the Clinical Research Center at Children's Hospital Medical Center.