While at Mass. Medicaid Dr. Master was responsible for all policies and programs. For a time he also chaired the Health Services Dept. of the Boston University School of Public Health. While at CMA, an experimental HMO caring for individuals with severe disabilities and AIDS, he also functioned as Principal Investigator of the Medicaid Working Group, a partnership to develop new reimbursement and clinical care programs for people with severe disabilities or chronic illness. In 2003 he joined the Commonwealth Care Alliance, a statewide nonprofit consumer governed care system whose mission is to expand clinical programs, those that serve individuals with chronic illness and disability, to a statewide scale.