The Equal Pay Act is often presumed to be an accomplishment of the feminist movement of the 1960s. In fact, it was spearheaded by female trade unionists, who first introduced the bill in 1945 as an amendment to the 1938 Fair Labor Standards Act. The bill was defeated, largely because of staunch opposition from business interests, but a coalition of labor activists reintroduced it every year until it finally passed in 1963.