This volume collects 19 original and provocative papers on the tectonic evolution of mountain systems to honor the great Canadian structural geologist Raymond A. Price on the occasion of the fiftieth anniversary of his first publications on the geological structure of the Canadian Cordillera. The papers address the question, “Whence the mountains?” that Ray first posed in a college essay. Demonstrating the scope of Ray’s influence, topics range from plate to outcrop scale, from geometry based on mapping and cross-section construction to theoretical processes based on finite-element models, from metamorphic processes to syntectonic deposition. The authors employ detrital-zircon, argon/argon, and fission-track geochronometry, global positioning system, deep seismic reflection and other geophysical methods, as well as strain measurement, kinematic analysis, and classical regional mapping and stratigraphy. Study regions range from the North American Cordillera and Appalachians to Siberia, New Zealand, Australia, and China, from Paleozoic to active systems.