This book introduces mathematical logic and related topics to undergraduates in computer science, math, and philosophy. Several minor errors have been corrected in the revised edition without changing the original pagination. Causey (U. of Texas, Austin) has designed the text to teach students how to construct and write informal but rigorous mathematical proofs using basic set theory, recursive definitions, and mathematical induction. Formalized sentential and predicate logic are also introduced, with an emphasis on semantical concepts.