This thesis develops a reading of Montaillou, un village occitan de 1294 à 1324 (1975) by Emmanuel LeRoy Ladurie in parallel with a theory of possibilities in history. It is argued that possibilities are fundamentally involved in the semantics of sociological concepts, in the nature of historical judgements, and in the way actions feature in historiography. The thesis addresses a variety of literature in historiography, sociological theory, the philosophy of social science, and the philosophy of history. The thesis is split into a Preface and 5 parts containing between them 24 chapters of varying lengths. The Preface defines the topic in relation to the work of Max Weber. Part 1 is the Introduction, and approaches the topic of possibilities in history through classical texts in sociology and the philosophy of history. Part 2 is an extended commentary on Montaillou and raises puzzles about how it works as a text. Part 3 analyses sociological concepts and historical judgements in terms of possibilities. Part 4 analyses action in history in terms of possibilities. Part 5 brings the theoretical apparatus developed in parts 3 and 4 back to Montaillou to offer commentaries which solve the puzzles raised in part 2. The strategy of the thesis is to grasp the role of possibilities in history by giving equal weight to theoretical analysis and historiographical commentary.