This dissertation explores the health care policy organizational field in the United States (U.S.) and its changes due to the implementation of the Patient Protection and Affordable Care Act (ACA). In particular, this study provides the interest groups' role in the ACA's evolution process. The ACA was enacted in 2010 by the US Congress highlighting some major reform goals, which included, i) expanding states' Medicaid expansions and health insurance market reforms to allow greater access to health care services for all Americans, ii) regulating health care providers and lowering costs, and iii) ensuring patient and consumer protection. The policy reform impacted the wide range of interest groups who were societal level actors representing the health care provider groups, hospitals, health insurance companies, and pharmaceutical companies, and patients, etc. The ACA emphasized changes in both structure and culture of the health care policy field to ensure greater institutional representation of the federal government in working with various actors in the health care policy field. This study followed two theoretical guidelines, which included 1) the new-institutionalism theory emphasizing the structuration, dependency, and legitimacy factors in actors' strategies in the health care policy organizational field and 2) Pierre Bourdieu's perspectives of the field focusing on the cultural, social and political, economic, and symbolic capitals and actors' habitus or predispositions due to the ACA in the health care policy field. Besides, the federal government, the states, and the roles of the five health care related professional organizations were investigated. These organizations included, 1) The American Medical Association (AMA), 2) The American Hospital Association (AHA), 3) The America's Health Insurance Plans (AHIP), 4) The Pharmaceutical Research and Manufacturers of America (PhRMA), and 5) The AARP Inc. (a.k.a. American Association for Retired Persons). I studied the testimonies of these organizations at the U.S. House of Representatives and the Senate and their lobbying activities as actors influencing the health care legislative policies. The qualitative analyses of both manifest and latent contents of the ACA's legislature and testimonies of the interest groups showed how different actors "wanted" the ACA to be and how they won and lost in the legislative process. Further, how the interest groups used various capitals to actuate the ACA implementation? A focus on the state level legislative processes amplified how the ACA's implementation is primarily reliant on the state level actors. This study aims to expand knowledge in the area of the health care policy change management. Further, the study provides cross-disciplinary knowledge exchange opportunity for other disciplines, such as, management, public policy, and health care administration to understand health care policy processes through sociological lens.