“Fragmentation” – the breakdown in communication among many providers treating a single patient, such that multiple decision makers make a set of health care decisions that would be made better through unified decision-making1 – is frequently cited as a major problem in the US health care system.2 It plagues both the payment system (which has multiple payers) as well as the delivery system (which has siloed providers). This chapter focuses on the latter problem of fragmentation among care providers and calls to correct it via “care coordination.” The problem is not just provider fragmentation, however. It is also the lack of clarity regarding what care coordination (the proposed solution) means, what benefits it confers, and how to do it.