This book constitutes the refereed conference proceedings of the 12th International Symposium, W2GIS 2013, held in Banff, Canada, in April 2013. The 11 revised full papers and 5 short papers presented were carefully selected from 28 submissions. The program covers a wide range of topics including Spatial Semantics and Databases, Location-based Services and Applications, Trajectory Representation and Sensor Web, Spatial Analysis and Systems and Map Generation and Modeling.