Determining geographic interpretations for place names, or toponyms, involves resolving multiple types of ambiguity. Place names commonly occur within lists and data tables, whose authors frequently omit qualifications (such as city or state containers) for place names because they expect the meaning of individual place names to be obvious from context. GeoWhiz is a system that demonstrates a novel technique for place name disambiguation (also known as toponym resolution). The system uses Bayesian inference to assign categories to user-specified lists of place names, then interprets individual toponyms based on the most likely category assignments. The categories are defined along three orthogonal dimensions: place types (e.g., cities, capitals, rivers, etc.), geographic containers, and prominence (e.g., based on population). A map interface enables users to explore possible interpretations and compare the interpretations that are most likely based on selected categories.