This report describes the results of the Specialist Meeting about “The Ontology of Fields” (Bar Harbor, Maine, June 11-13, 1998). The main purpose of the meeting was to examine the ontology and conceptualizations of geographic phenomena in terms of spatially continuous fields. The concept of field is widely used in a variety of scientific contexts, most notably in mathematical physics, and many geographically distributed variables (e.g., elevation and temperature) are conceptualized as single-valued functions of location. This document explores questions addressed at the meeting regarding the nature, representation, and modeling of fields. It also summarizes discussions among invited experts and provides abstracts of presentations.