This book, suitable for use in a one-semester introduction to electrodynamics for advanced undergraduates, emphasizes relativity and symmetry in developing the theory. By focusing immediately on the Lorentz invariance of Maxwell's equations, the presentation makes many advanced topics readily accessible to the student. After a brief review of the history of electrodynamics, the book presents the experimental basis for the four Maxwell equations, both in vacuo and in dielectric and magnetic media. The principle of relativity is then used to unify the equations into a pair of covariant field equations, and steady-state solutions of these are treated both analytically and numerically. The final chapters discuss radiation in a vacuum and in dielectric media; the motion of charged particles in electromagnetic fields; radiation by moving changes; and, briefly, extensions to quantum theory. Mathematica scripts on the included diskette provide graphic solutions to many of the examples discussed in the text.