In this article, the author advances a theory of intermediary behavior that anticipates that controlled forms of intermediary failure will occur with regularity even in the most successful certification markets. In Part II, he reviews the intermediary thesis and the mixed body of empirical support. In Part III, he reviews the economic characteristics of certification markets together with illustrative evidence. In Part IV, he describes the certification paradox. In Part V, he argues that the certification paradox and associated informational constraints cast doubt on traditional regulatory tools to improve certifier performance. In Part VI, he discusses the use of organizational forms to limit certifier opportunism, together with evidence from financial and social certification markets. Even if the market's self-corrective capacities are far more limited than has been commonly assumed, the risk of regulatory failure may be so great that this existing market "failure" is the best-available state of affairs.