INSTITUTIONAL CONSTRAINTS ON SOCIAL-MOVEMENT FRAME EXTENSION - SHIFTSIN THE LEGISLATIVE AGENDA OF THE AMERICAN-FEDERATION-OF-LABOR, 1881-1955

''Frame extension'' is an important frame-alignment strategy for incre asing social movement membership. Little research has addressed how th e institutional environment of a social movement organization constrai ns and compels the organization to extend its frame among potential ad herents. Elaborating on the bargaining perspective and the concept of multiorganizational field we develop market and political models of th e impact of social movement dependence relations with movement antagon ists and political opportunity on frame extension. Our examination of these models with a multivariate time-series regression analysis of ch anges in the legislative agenda of the American Federation of Labor (A FL) over its complete history suggests that the AFL extended its frame among potential adherents in response to declining employer dependenc e on unions for labor-supply and increasing political opportunity. We conclude with implications of the findings for future research on cont emporary union decline and institutional and environmental influences on social movement frame-alignment processes.