Service Employees International Union is one of the largest labor unions in the United States and Canada. The union, often called SEIU, consists of more than 300 local unions in the two countries. It represents service workers in over 100 occupations. These occupations are organized into five main divisions: health care, public employment, office and clerical, building service, and light industrial. Women make up half the membership. SEIU is affiliated with the Change to Win labor federation.