This Collaboration Case Note describes TAI efforts to foster collaboration on improving fairness and transparency in the international tax system. TAI Secretariat and members shared experiences, tips, and advice, attended conferences and workshops, disseminated and exchanged information, and compared their strategies. This collaboration yielded process-r elated changes for information sharing, a mapping of strategies and actors, and more aligned and informed grantmaking. It also had reach beyond TAI and generated interest among other funders. Bigger picture goals around tax system change have gone largely unrealized, as the collaboration purpose shifted away from the initial aims of strategy development or pilot programming.