Extensive work has been carried out during the past few years to explore the significance of gas generation and release in radioactive waste repositories, and to determine to what extent the associated phenomena have to be taken into account in the planning, design, and safety assessment of repositories. A recent workshop organized by the OECD Nuclear Energy Agency and ANDRA (France) brought together experts from many NEA countries to discuss issues of common concern in this field. These proceedings reproduce the papers presented at the workshop together with an extensive record of the discussions, and summarize the state of knowledge on most issues related to gas generation and release in radioactive waste repositories. (U.K.)