[Extract] This Special Issue of the Int. J. Geomech. on soft clay engineering and soft clay improvement is a result of discussion among various colleagues during the Geo-2000 Conference in Melbourne, where the need for a Special Issue on soft clay engineering and improvement was raised. The papers contributed to this Special Issue are selected to reflect the latest developments relating to soft clay engineering and improvement, and address research and applications in many places around the world (e.g., Australia, Finland, The Netherlands, Norway, Singapore, United Kingdom, and the United States). This Special Issue covers a variety of aspects for soft clay engineering and improvement, including constitutive modeling, numerical and analytical methods, design parameters, field and laboratory testing, and case studies.