This graduate-level text is a product of the author's course in advanced quantum mechanics, taught many times at the University of Massachusetts, Amherst. It offers students a thorough grounding in nonrelativistic techniques related to its full relativistic treatment, including material on nonrelativistic Feynman diagrams and their application to electromagnetic process. Topics include propagator methods, scattering theory, charged particle interactions and their applications, alternate approximate methods, and the Klein-Gordon and Dirac equations. Problems appear in the flow of the discussion, rather than at the end of chapters. An abundance of content makes this text more than adequate for single-semester courses, and supplemental material — designated by an asterisk — is provided for dedicated readers.