1. Total number of members or subscribers in a managed care plan at a given time. 2. Conversion of an eligible group into managed care plan membership. Some group plans have conditions of the minimum size or minimum percentage of a group that must enroll before insurance coverage is available. See also open enrollment period . 3. Process by which an individual becomes a subscriber for coverage in a health plan. 4. Process by which a Medicaid-eligible person becomes a member of a managed care plan. Enrollment data refer to the managed care plan’s information on Medicaid-eligible individuals who are plan members. The managed care plan gets its enrollment data from the Medicaid program’s eligibility system. 5. Information confirming that an individual is enrolled in a health insurance plan.