As health care organizations create larger networks, better coordination of primary and specialty care is paramount. Attention has focused on strengthening primary care by creating patient-centered medical homes. The "medical neighborhood" provides a framework for structured, reciprocal relationships that integrate specialty care and extend the principles of the medical home to all practicing physicians. The foundation of the medical neighborhood is the collaborative care agreement, which outlines mutual expectations for primary care physicians and specialists as they care for patients together. These expectations include a preconsultation exchange between the referring physician and the consultant, the consultation, and subsequent comanagement of patients over time. Although independent practices can create individualized collaborative care agreements with specific specialist colleagues, large health care provider networks and accountable care organizations should have 1 agreement for all affiliated physicians. Challenges to the medical neighborhood include fee-for-service reimbursement, existing referral relationships, and building a robust electronic platform, including a referral management module. Cooperation between physicians, regardless of their specialty, and innovation in payment models and electronic platforms will all be essential if medical neighborhoods are to succeed.