Legitimacy is vital to unions. Without it, they lose political and ideological support, members, and access to funds. Gary Chaison and Barbara Bigelow use the concept of legitimacy as a lens through which to understand the steady decline in union size and influence and to suggest new strategies for union revitalization.Chaison and Bigelow relate legitimacy to five case studies: the UPS strike, the organization of clerical workers at Harvard, the AFL-CIO associate membership campaign, the fight against NAFTA, and the Massachusetts Nurses Association Campaign for Safe Care. The cases show the need for unions to move beyond pragmatic concerns and link their activities to the broader interests of their constituencies, demonstrating not only that they offer something tangible in return for support (pragmatic legitimacy) but also that they are doing the right thing (moral legitimacy).Chaison and Bigelow's work has practical implications for the management of unions' core activities--organizing, collective bargaining, and political action.