This book constitutes the refereed proceedings of the 4th International Conference on Geometric Modeling and Processing, GMP 2006, held in Pittsburgh, PA, USA, July 2006. The book presents 36 revised full papers and 21 revised short papers addressing current issues in geometric modeling and processing are addressed. The papers are organized in topical sections on shape reconstruction, curves and surfaces, geometric processing, shape deformation, shape description, shape recognition, and more.