The educational system is the most important of the institutions that bridge the family and the work place. Because of the role of bridge institutions in providing skills and screening that influence an individual's developmental path, it is important to understand how urban systems allocate scarce opportunities. The purpose of this essay is to describe two models of the opportunity system. The first model, the exchange model, is derived from principles of neo-classical economic theory, and draws upon a well-defined literature. The second model, the grants economy approach, focuses upon nonexchange behaviors that influence opportunity generation. Both models, however, provide insights into two central questions: (1) What determines the developmental opportunity system that confronts individuals? and (2) What principles determine access to alternative paths? (Author/GC)