This article aims to study the design and the organization of auditing systems to develop environmental or quality assurance schemes at the farm level and the role that extension services could play in these processes. It starts by discussing the issue of combining auditing and advisory activities and developing auditing competences. Empirical data is based on a case study conducted in northern France with Chambers of Agriculture including: a) the study of the organizational design set up for the auditing system in order to guarantee its credibility and reliability; b) the analysis of audit training sessions delivered to agricultural advisers. Our results provide a formalization of what can be an audit work and the independence of the auditor. It is argued that the interpretation of independence and the management of the human resources and their competencies determine how extension services get involved in quality assurance systems at the farm level. (Contains 4 tables, 2 figures, and 1 note.)