Opportunity structures
（重定向自Opportunity structure）
Opportunity Structures, in sociology and related social science disciplines, are exogenous factors which limit or empower collective actors (social movements). In explaining the evolution of social movements, the structuralist approach emphasizes that factors external to the movements themselves, such as the level and type of state repression, or the group's access to political institutions, shape the development of the movement; such factors are called opportunity structures.