In recent difficult economic times, the efficiency with which a charity spends the funds entrusted to it has become an increasingly important aspect of charitable performance. Transparency on efficiency, including the reporting of relevant measures and information to understand, contextualize, and evaluate such measures, is suggested as important to a range of stakeholders. However, using a novel framework for the analysis of efficiency reporting in the context of transparency and stakeholder theory, this research provides evidence that reporting on efficiency in U.K. charities lacks transparency, both in terms of the extent and manner of disclosure. It is argued that efficiency reporting in U.K. charities is more concerned with legitimizing these organizations rather than providing ethically driven accounts of their efficiency.