Windows and Agendas. When these three streams - problem, political and policy - meet, a public policy can result. Kingdon calls these occasions windows. Windows open because of a change of administration, changes in Congress, a shift in the national mood, or when a pressing public problem emerges. When the window opens that results in a restructuring of the governmental agenda, it could be solely the result of occurrences in either the problem stream or the political stream But for a window to open that results in a restructuring of the decision agenda require the joining of all three streams. In this latter case, the role of the policy entrepreneur is critical, and entrepreneurs must have legitimacy, connections, and persistence to be successful.