Interrogative clauses in French show abundant variation, especially with regard to the position of the subject vis-à-vis the finite verb, the placement of the wh-word, and the use of question markers such as est-ce que and ti/tu. This book presents a comprehensive study of the evolution and use of French interrogative constructions across a time span of approximately five hundred years by drawing on written sources (15th to 17th century) and oral data (19th and 20th century). Special attention is paid to the regional variation between European French and Quebec French. A variationist analysis reveals the relevant sociolinguistic factors conditioning variant choice. On the basis of the results obtained, the syntax of the different variants is modeled within the framework of generative grammar. In particular, the progressive diachronic decline and restriction of subject-verb inversion is argued to mirror the loss of verb movement.