Many branches of abstract mathematics have been affected by the modern independence proofs in set theory. This book provides an introduction to relative consistency proofs in axiomatic set theory, and is intended to be used as a text in beginning graduate courses in that subject. It is hoped that this treatment will make the subject accessible to those mathematicians whose research is sensitive to axiomatics. The readers should have had the equivalent of an undergraduate course on cardinals and ordinals, but no specific training in logic is necessary. The volume includes a discussion of modern techniques in forcing, as well as coverage of infinitary combinatorics and its relevance to independence proofs. The work also features a lucid treatment of basic facts about constructibility.