Coastlines and their mangrove forests change over time under the influence of human and natural drivers. To design appropriate mangrove reforestation interventions, we use the Vietnamese province of Soc Trang, at the Bassac River mouth, as a case study to understand coastal zone changes. Our research, covering 1904–2007, is based on historical material from the French colonial period (topographic maps, reports), satellite images, and onsite interviews with key informants.