Publisher Summary This chapter discusses the advances in both global and regional understanding of Quaternary history, deposits, and geomorphic processes that have brought new information and new techniques for characterizing the growth, decay, and products of the Cordilleran Ice Sheet during the Pleistocene. The Cordilleran Ice Sheet, the smaller of two great continental ice sheets that covered North America during Quaternary glacial periods, extends from the mountains of coastal south and southeast Alaska, along the Coast Mountains of British Columbia and into northern Washington and northwestern Montana. Ice has advanced south into western Washington at least six times, but the marine-isotope record suggests that these are but a fraction of the total that entered the region in the past 2.5 million years. Reconstruction of the Puget lobe of the Cordilleran Ice Sheet during the last glacial maximum requires basal sliding at the rates of several hundred meters per year, with pore-water pressures nearly that of the ice overburden. Landforms produced during glaciation include an extensive low-gradient outwash plain in front of the advancing ice sheet, a prominent system of subparallel troughs deeply incised into that plain and carved mainly by subglacial meltwater, and widespread streamlined landforms.