The history of the French language has emerged from lectures and seminars that Prof. Johannes Klare has been conducting since 1957 at the Romance Studies Institute of Humboldt University in Berlin. The complex and intricate formation and development of the approximately ten Romance languages from Latin, specifically from the various regionally and socially differentiated varieties of spoken Latin, are of particular interest in research and teaching. This work by Klare, made available again in a new edition due to constant demand, takes a unique approach compared to other handbooks and raises questions that have been addressed in recent Romance studies literature but have received little to no attention in handbooks on Gallo-Roman language development.