This is a first course in two of the 20th century's most exciting contributions to physics: special relativity and quantum theory. Historical material is incorporated into the exposition and nearly every section contains at least one illustrative example (with all calculations), and each chapter has a wide selection of problems. Topics covered include relativistic dynamics, quantum mechanics, parity, quantum statistical physics, the nuclear shell model, fission, fusion, colour and the strong interaction, gauge symmetries, and grand unification.