This book constitutes the refereed proceedings of the First International Conference on GeoSpatial Semantics, GeoS 2005, held in Mexico City, Mexico in November 2005.

The 15 revised full papers presented together with 4 short papers were carefully reviewed and selected from 42 submissions. The papers are organized in topical sections on theories for the semantics of geospatial information, formal representations for geospatial data, similarity comparison of spatial data sets, ontology-based spatial information retrieval, and geospatial semantic Web.