"The Footprint Evaluation Initiative aims to ensure that all evaluations consider environmental sustainability, regardless of whether this is an explicit objective of the project, policy or program being evaluated. This report describes four ‘thought experiments’ undertaken as part of this project. The thought experiments explored whether it is relevant, feasible and useful to consider environmental sustainability in evaluation, how this might be done, what challenges and issues it raises, and what is needed to address these. This report aims to document and share what we learned during this process, provide concrete examples of how environmental sustainability might be considered in an evaluation, and share details of our thought experiment process that others might find helpful." (Summary)