To compare the efficacy, based on the bone turnover marker (BTM) serum Type I collagen C-telopeptide (CTx), of a 50 mg delayed-release risedronate tablet, administered immediately after a typical breakfast, to that of a 35 mg immediate-release tablet, administered according to labeling instructions (ie, at least 30 minutes prior to breakfast) in postmenopausal women after 13 weeks of treatment.