This book provides theoretical and practical guidance on the accountability mechanisms used by the Public Prosecutor's Office to monitor private law foundations. In view of the growing importance of third sector institutions in today's society, this book seeks to identify the supervisory nuances that guide probity in this organisational sphere. To this end, it discusses the ontological aspects of the Public Prosecutor's Office and Foundations, culminating in an analytical and innovative interpretation of the auditing practices inherent in this control relationship. Thus, the theoretical framework contained in these pages makes it possible to improve the current accountability mechanism (SICAP) used by the Foundations and the Public Prosecutor's Office in 22 Brazilian states, providing the necessary guidelines for a broader and more efficient audit of accountability.