This paper provides an analysis of the structure of the health care delivery system, emphasizing physician group practices. The authors argue for comprehensive integrated delivery systems (IDSs). The jumping-off point for their analysis is the recently published Redefining Health Care: Creating Value-Based Competition on Results, by Michael Porter and Elizabeth Teisberg. The authors focus on the book's core idea that competitors should be freestanding integrated practice units (or "islands in archipelagos") versus IDSs (or "medical homes"). In any case, the authors contend that this issue should be resolved by competition to attract and serve informed, cost-conscious, responsible consumers on a level playing field.