Tai Chi for Osteopenic Women

Inclusion Criteria: * Women ages 45-70 years * BMD T-scores of the hip (femoral neck or trochanter) and/or spine between -1.0 and -2.5 * Post-menopausal w/out menses for ≥ 12 months * Sedentary, i.e. do not regularly participate in physical exercise on average 1 or more times per week Exclusion Criteria: * Osteoporotic (T-score \< -2.5) or a fracture in the past 2 years not caused by motor vehicle accident * Prior or current use of use of medication that increase risks of fracture (e.g. steroids, anti-convulsants, anticoagulants, lithium) * Prior or current use of medications that modify bone metabolism (e.g. bisphosphonates, selective estrogen receptor modulators such as Raloxifene) * Use of calcium supplements above levels suggested within the recommendations of standard care (i.e., above 1200-1500 mg) * Current or prior year use of estrogen or calcitonin * Malignancies other than skin cancer * Diagnosis of anorexia along with a BMI of \< 17.5 * Conditions that cause secondary osteoporosis (e.g. Cushing's syndrome, Marfan's syndrome) * Tobacco use in past year * Physical or mental disabilities that will preclude informed consent or active study participation * Geographic or scheduling limitations that would preclude required participation in weekly Tai Chi classes and study procedures * Current regular practice of Tai Chi