The Introduction begins with a brief outline of Pascal’s Wager and a review of the many reasons why this celebrated argument has enduring importance both to philosophers and to the public at large. These include its significance to the origins of decision theory, its dramatic approach to one of the core issues in Christian theology, and the questions it inspires about prudential and evidential reasoning, infinite utility, and the nature of religious assent. The next two sections provide an overview of standard (finite) decision theory and its extension to a simple version of infinite decision theory, one that plausibly approximates Pascal’s own views and the framework used in most philosophical discussions of Pascal’s Wager. The authors then employ this framework by presenting (in translation) the main texts of the Pensées in which Pascal develops his Wager argument, together with their decision-theoretic analysis. Following a brief review of major objections to Pascal’s argument, old and new, the Introduction concludes with a full set of summaries for all contributed chapters.