This report evaluates the IMF’s effectiveness in collaborating with the World Bank as the Fund worked to raise the quality and influence of its work on macro-structural issues and contain costs. It focuses in particular on IMF pilot initiatives to enhance coverage of inequality, gender, energy/climate, and macro-structural reforms in Article IV surveillance. The evaluation found overall that IMF collaboration on macro-structural issues has been broad but uneven. While informal consultation was widespread, initial aspirations that the Fund would be able to systematically leverage Bank expertise proved over-optimistic, and we found relatively few examples of in-depth collaboration. This reflected in part the decentralized approach adopted in the pilots, but also resulted from a tendency toward self-reliance on the part of Fund staff as well as the institutional complexities of working with the Bank, including finding access to the right people and inputs and aligning goals and timetables. The evaluation concluded that collaboration can bring significant benefits to the quality and influence of Fund work but also poses challenges and is not a panacea for extending the Fund’s ability to cover a widening range of issues at a time when resources are under strain. It recommended that the IMF develop and agree on concrete frameworks to ensure effective collaboration with the World Bank on key macro-structural issues (such as climate) where collaboration is judged to bring the greatest strategic returns. Recognizing that more effective collaboration depends not only on the Fund, but also on other partners, the evaluation also recommended that the Fund improve internal incentives and address the wider cultural reluctance to engage with external partners; work with the World Bank to improve access to and exchange of information and knowledge across the two institutions; and strengthen the strategic role of the Executive Board in facilitating and supporting external collaboration.