A patient-centered medical home provides coordinated care and enhanced access to physicians (for example, by phone or e-mail, or after regular hours), makes use of clinical decision support tools and health information technology, engages patients in their care, and undertakes performance measurement and quality improvement activities. Two large health plans in New York are conducting a demonstration to promote medical homes by helping physician practices redesign their offices and revising the way they are reimbursed for patient services. The project team will evaluate this demonstration to determine if it is feasible to transform practices into medical homes and to assess the impact such a change has on quality of care, patients' care experiences, and the total costs of care.