Non‐government funders (NGFs) are major contributors to the third sector. Literature on this private philanthropic world is limited and access to stakeholders and practices within these institutions is a barrier to empirical research. With public oversight limited to nominal federal tax law disclosure, issues of accountability are under‐researched. We examine how NGFs ‘account’ for their grant making decisions in an Australian context. Focused on how NGFs assess likely success, it finds that assurance is constructed as part of the decision‐making process through a more socialising form of accountability, based on personal interaction, in contrast to a reliance on hierarchical accountability and transparency.