Organised interests play a double role in policymaking: as representatives of societal interests and as policy experts adding to regulatory quality. The former of these 2 roles has been examined over and over again, whereas the latter has almost completely evaded scholarly interest for a number of reasons. One reason is that it demands a focus on output rather than on traditional darlings such as representation, input legitimacy, or influence. Another is that it demands an interdisciplinary approach as regulatory quality—that which the involvement of organised interests seek to furnish—is a concept that includes elements from both law and political science. The question of how to design involvement of organised interests in order to support regulatory quality, however, is a question with both academic and practical relevance. Building on an empirical study, this paper attempts to spur theorising to address this relevant question. The result is 4 assumptions that describe the relationship between involvement of organised interests and regulatory quality.