The Affordable Care Act included funding for the piloting of the integration of mental health and physical health, a model that may help address poor outcomes and low quality of care for persons with mental illness. There is growing interest in this model and evidence for its effectiveness. This paper explores the development of the integration of physical and mental health care from an idea to a paradigm and explores how a model that has gained national attention can be implemented and spread at a local level. Using frameworks such as Kingdon's three streams model and the Advocacy Coalition Framework, as well as diffusion of innovation theory, in this study I look at the role that advocates, evidence, values, and policy played in the spread of the integrated health care model. This research triangulates three methods: a careful review of the literature, a systematic review of government policy documents, and in-depth policy interviews with key stakeholders and other experts in the field. I used non-probability and convenience sampling to identify potential participants based on positions of leadership and expertise related to integrated health care in North Carolina. I coded interviews and analyzed them for common themes. I interviewed six participants who represented elected government, bureaucratic government, academia, and advocacy. In the view of the participants, the spread of integrated care is driven by recognition of a problem, the view that integrated care is an attractive solution, and the excitement and collaboration of stakeholders. Participants also agreed that the integrated care model will be important in the future, becoming a permanent fixture in the way that primary care is practiced and the way persons with mental illness are treated. Their views, however, differed on the role of research, with half of the participants seeing research as not important in the spread of integrated care. Identified barriers to dissemination included payment models, cultural differences between providers, and a lack of clear definitions. Suggestions to overcome these barriers included creating a means for proponents to share lessons and clear definitions to facilitate communication.