Coastal subsidence is a geological phenomenon that affects several littoral and deltaic regions with their environmental and depositional systems. This process consists of vertical displacement of the land relative to sea level. Although subsidence can be a direct hazard (e.g. landslides and sinkholes), more commonly it is associated with hazards that are exacerbated by subsidence cumulative effects, like sea level rise, flooding, erosion and the integrity of coastal water defences. The natural displacement of coastal lands, coupled with subsidence triggered by human activities, can lead to topographic, ecological and geological modifications or to land collapses, with concomitant consequences in the landscape patterns and serious impacts on human resilience and the structures where humans live. This chapter aims to provide a comprehensive review of the state of the art of coastal subsidence and to deliver reliable information for stakeholders, public entities and scientists by three main pillars: (1) the analysis of its natural and anthropic causes, (2) the use of innovative monitoring techniques and (3) the description of real cases, with proper follow-up in the implementation of new methodologies and scientific progress in the field.