Einstein's general theory of relativity is introduced in this advanced undergraduate textbook. Topics covered include geometric formulation of special relativity, the principle of equivalence, Einstein's field equation and its spherical-symmetric solution, as well as cosmology. The writing is authoritative and lucid, and the author follows a solid development of the special and general theories of relativity before introducing contemporary cosmology. The presentation is streamlined in terms of selection of topics, but this allows a comprehensive discussion of the subject matter. ... Recommended.