Radioactive waste is associated with all phases of the nuclear fuel cycle as well as the use of radioactive materials in medicine, research and industry. For the most hazardous and long-lived waste, the solution being investigated worldwide is disposal in engineered repositories deep underground. The importance of geoscientific information in selecting a site for geological disposal has long been recognised, but there has been growing acknowledgement of the broader role of this information in assessing and documenting the safety of disposal. The OECD/NEA Approaches and Methods for Integrating Geological Information in the Safety Case (AMIGO) project has demonstrated that geological data and understanding serve numerous roles in safety cases. The project, which ran from 2002 to 2008, underscored the importance of integrating geoscientific information in the development of a disposal safety case and increasingly in the overall process of repository development, including, for example, siting decisions and ensuring the practical feasibility of repository layout and engineering.