It is the purpose of this book to provide an introduction to the Special Theory of Relativity which is accessible to any student who has had an introduction to general physics and some slight acquaintance with the calculus. Much of the material is at a level suitable for high school students who have had advanced placement in physics and mathematics. Since some of the exposition, particularly part of Chapter 6, is presented here in book form for the first time, even terminal graduate students in physics may find the material profitable. The subject matter of the book has been taught, in the form presented here, to first-year graduate students at Kansas State University for many years. Much of it has sifted into courses at
lower level. The typescript was read by Professors E. U. Condon, University of Colorado, and Melba Phillips, University of Chicago. I wish to thank them for their helpful criticism and valuable suggestions.