This text focuses on the latest discoveries on calreticulin, calnexin and other endoplasmic reticulum proteins. Calreticulin has been implicated to affect diverse cellular function and play a role in many pathologies including protein folding disorders, cardiac pathologies, cancer and autoimmunity. The book contains contribution form the world leaders in the area of endoplasmic reticulum function, protein folding, calcium homeostasis and autoimmunity. It raises many questions about calreticulin, calnexin and the endoplasmic reticulum and gives an opportunity to realize the significance of these calcium-binding chaperones.