Economic regulators use various instruments to stimulate SMEs to change their behavior, but limited evidence exists on the effectiveness of such interventions. We analyze the effectiveness of three ways of providing e-commerce firms guidance about the legal rules on information disclosure. The initial non-compliance is considerable. In two interventions, firm-specific guidance is given by post mail and by e-mail, respectively; in another intervention, guidance on industry level is given by means of dedicated publications and presentations. In all cases, the guidance was given on behalf of the regulatory authority. The effectiveness of the firm-specific guidance is measured through a randomized field experiment, while for the industry guidance a panel analysis is conducted. We find that sending the firms a letter by post mail slightly improved firm compliance, but overall the various forms of guidance appear to be ineffective. Although information-related interventions are commonly used in practice, such regulatory interventions can fail to influence the behavior of SMEs.