This chapter compares trade unions in the United Kingdom, the Federal Republic of Germany, and the United States in order to show how and why they differ and and what they have in common, to better explain each of the three labor movements. Space being limited, the inquiry focuses on why workers join or do not join a union, how they structure their organizations, and why they strike. It concentrates on the influence social and political environments have on union membership and structure and looks into the relationship between membership, structure, and strike behavior. The economic motives of union activities are not investigated, and the union's political activities are examined only in passing. Their history, however, will have to be examined, as present patterns can be understood only if past events are taken into account. Because comparative research on labor unions is a new field, many of the statements that follow should be regarded as hypotheses in dire need of empirical corroboration. 1