Boccaccio, Chaucer, and Stories for an Uncertain World understands the Decameron and the Canterbury Tales to communicate a radical uncertainty haunting most human endeavors, one that challenges effective knowledge of the future, the past, or the distant present; accurate perception of both complex, equivocal signifying systems, including language, and the intentions hidden rather than revealed by the words and deeds of others; and successful strategy in dealing with the chronic excesses and arbitrariness of power. This comparative study of Decameron novelle and Canterbury pilgrim tales yields the insight that the key to coping with these challenges is pragmatic prudence: rational calculation issuing in an opportunistic, often amoral choice of ingenious deeds and/or eloquent words appropriate (though without guarantee) to mastering a specific crisis, and achieving the goal of agency in the here and now, not salvation in the Hereafter. An initial chapter explores the Aristotelian antecedents, contemporaneous cultural influences, and narrative techniques that intersect to shape the radically uncertain world of the Decameron and the Canterbury Tales, while succeeding chapters pair, and compare, stories from both collections that illustrate the quest for agency - its successes and its failures - through plots often brilliantly adapted from simpler antecedents, as well as eloquence by turns satiric and insightful. This is storytelling that exposes a culture's fears, as well as its aspirations for mastery over the circumstances that challenge its existence; reading these tales should be a labor of love and the goal of this study is to help assure that the reader's labor shall not be lost.