A leading American authority on Quebec and U.S.-Canadian relations examines the intimate and complex relations between the French colonies of Canada and Louisiana from the initial explorations of the Mississippi valley by men of New France and their subsequent settlement and administrative, political, and economic leadership of Louisiana well into the period of Spanish control following the Seven Years War. This book traces persisting controversies between Louisiana's Canadian elites and their Native-European French counterparts in Canada and the different social, religious, and economic evolutions of the two French colonies. Hero subsequently explores the sharp decline in communications between Louisiana and Quebec and the continued mutual social, cultural, and economic divergence under the Spanish contrasted with the British. That comparative analysis continues after the Louisiana Purchase until the Second World War, by which time the great majority of Canadians and others of French descent, save the Acadians and francophone nonwhites living and working apart from the American majority, no longer spoke French. This book continues with the accelerated assimilation of most of the children and grandchildren of the remaining French speakers, notwithstanding growth in active educational and other cultural collaboration of Louisiana with Quebec following 1969 and then the decline in bilateral collaboration since 1985. Hero ends with a thoughtful appraisal of how cooperation between the two might more fruitfully develop as ever smaller minorities of Louisianans continue to speak French. Co-published with the Tulane University Series in Political Science.