The CHOICE study is documenting dual eligible consumers' health care decisions and experiences with California's duals demonstration program in Los Angeles County. Between April 1, 2014 and March 31, 2015, dual eligible consumers (i.e., those eligible for both Medicare and Medi-Cal) were enrolled into a managed care program called Cal MediConnect unless they actively opted out. The Cal MediConnect program is designed to integrate the financing and delivery of Medicare and Medi-Cal benefits and provide consumers with better coordinated care. Yet uptake and retention of Cal MediConnect is falling far below expectations and reported “opt-out” rates vary by age, race/ethnicity, and primary language of the consumer. We conducted in-depth interviews with 48 dual eligible consumers who either “opted out” or were enrolled in Cal MediConnect. Using a constructivist grounded theory approach and constant comparison analysis, we identified a complex set of factors that influence consumer decision making and documented the processes by which consumers make these decisions. We developed case studies that illustrate how consumers evaluated the options available to them and highlight age and racial/ethnic differences as evidenced across our sample. Understanding how individuals make health care decisions will help inform strategies for effectively communicating and responding to the preferences of a diverse group of dual eligible health consumers, while also identifying practices that better support health-related consumer decision-making.