The book provides the first comprehensive discussion of optimal search theory in a spatial context. By treating the alternatives of a search problem as spatially distributed, the standard structure of an optimal search model is altered considerably. The book discusses the basic structure of this spatial search problem and demonstrates that it falls into a class of highly complex problems. After a brief discussion of potential simplifications and heuristic solutions it applies the microeconomic concept of spatial search to selected aspects of spatial economics like spatial price theory, the theory of market areas, and agglomeration theory. It can be demonstrated that a spatial search based theory can capture a number of well known phenomena, e.g. the transition from a dispersed to an agglomerated locational pattern.