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.