SEIU Local 509 represents nearly 20,000 human service workers and educators throughout Massachusetts. We provide a variety of social services to elders, at-risk children and people with mental illnesses or developmental disabilities — as well as educational services in both public and private sector settings. From mental health clinicians and social workers to early childhood educators and university lecturers, Local 509 members are united in our mission to raise living standards for all working families while improving the quality and affordability of the services we provide. SEIU Local 509 is part of the 2.1 million member Service Employees International Union, the fastest-growing labor union in the United States. Focused on uniting workers in four sectors — public services, long term care, property services, and hospital systems — SEIU is the nation’s largest health care union, the largest property services union, the second-largest public employee union and the fastest-growing union in early childhood and higher education.