Public Expenditure Tracking Surveys, or PETS, are recognised as an effective tool to improve accountability in public finance and service delivery. A Ugandan success with PETS is one of the most cited anti-corruption success stories. Expenditure tracking has also become a popular activity among civil society organisations engaged in accountability issues at the local level. This U4 Issue Paper takes a closer look at the experience of expenditure tracking and argues that its successes may have been overstated. It suggests that an uncritical acceptance of the effectiveness of expenditure tracking has hindered the development of a more nuanced approach that is better suited to the particular circumstances of each case. The paper proposes some principles of engagement on how to track expenditures more effectively.