The interaction between organised interests and policy makers is an important ingredient of contemporary political systems. In earlier work, interest group scholars have distinguished groups that enjoy access to consultation arrangements from those that are bound to stand on the sideline. Frequently, these insiders are considered to be equally connected to public authorities. Yet their degree of ‘insiderness’ differs significantly. By unpacking the set of organised interests that have gained access, this article distinguishes core insiders from groups that occupy a more peripheral position in an interest intermediation system. Empirically, we demonstrate and explain varying degrees of insiderness in the community of insider groups in Belgium, using the extensiveness of representation in advisory bodies as a proxy for access. Our findings show that, although nowadays a diverse set of organised interests gets involved in policy-making processes, the inner circle is dominated by traditional economic interests.