Researchers from HRA at UC Berkeley’s School of Public Health collaborated with the California Department of Health Care Services and the California HealthCare Foundation, to conduct a rigorous and representative study of the experiences of seniors and people with disabilities (SPD) during and immediately following the transition from fee-for-service to Medi-Cal managed care. The objective of the study was to assess the prevalence of positive, negative and neutral experiences with notification, choosing a plan, and access to care in their new plan. Additional analysis identified subgroups of beneficiaries who had negative experiences and require additional support during delivery system transitions. Results informed state and federal program officials, legislators, health plan managers, consumer advocates, and other stakeholders. Results are particularly relevant for ongoing efforts to transition SPDs into managed care plans, including the Coordinated Care Initiative, in which SPDs who are dually eligible for Medicare and Medi-Cal will be transitioned to managed care plans beginning in the Spring, 2014.