Regulation is now considered as essential to bring microfinance institutions to formalization and to protect clients. Yet, most studies investigating regulatory issues focus on formal regulation, namely laws, or on the way other forces, just like competition, influence the market. This note presents the key findings of a research exploring a third regulatory mode: industry self-regulation and the role played by professional associations. Through a case study based on the Tanzanian microfinance association, this research draws conclusions on factors that may favor or restrain the potential of such organizations to contribute to the general regulatory framework.