This book is about calreticulin, a multifunctional calcium binding protein first discovered over 20 years ago. The protein has been described in various locations: endoplasmic reticulum, nuclear envelope, cytoplasmic granules, nucleus, cell surface and even secreted into the blood stream. This volume outlines the newly discovered functions for calreticulin including its control of calcium homeostasis, modulation of steroid-sensitive gene expression, control of viral RNA replication, modulation of nuclear transport, role in T lymphocyte activation and cytotoxic killing, chaperone function, control of adhesion-dependent signaling via integrins, possible role in the biology of ticks, in the pathology of autoimmune diseases and in blood function.