This book gathers the peer-reviewed papers presented at the Third RILEM International Conference on Earthen Construction (ICEC), held in Lisbon, Portugal, on 7–10 July 2026. It highlights the latest advances and innovations in the field of earth-based building materials and construction. The conference topics encompass material characterisation, hydro-mechanical behaviour, reinforcement behaviour, seismic behaviour, in situ and field testing, additive manufacturing (3D printing), rheology, biostabilisation, microstructure, durability, fire performance, hygro-thermal behaviour, life cycle analysis, climate change adaptation, economic impacts, earthen architecture and culture heritage. As such, this book represents an invaluable, up-to-the-minute tool and offers an important platform to engineers, architects and geophysicists.