The book gives theoretical foundations of technological processes for melting, casting, forming, heat treatment and welding of Al-Li alloys. It contains a critical survey of the research in the field and presents data on commercial Al-Li alloys, their phase composition, microstructure and heat treatment of the ingots, sheets, forgings, and welds of Al-Li alloys. The book is illustrated with the examples of Al-Li alloys application in aircraft structures. Based on the vast experience of the co-authors, the book presents recommendations on solving practical problems of melting and casting ingots, welding of aluminum-lithium alloys and producing massive stampings for welded products.