Interest groups are widely perceived as channels through which societal interests express their policy preferences/ demands and as key actors in effective problem solving at European Union (EU) level. This chapter provides the informative value of these indexes by empirically investigating plurality within EU environmental policy, across five open consultations. It addresses a key topic in the literature regarding the choice for a suitable label for characterising the EU interest representation system and by providing one of the few disaggregate empirical investigations of the EU interest group system based on groups’ policy demands. The chapter proposes an alternative approach to the measurement of plurality of private actors’ voices and levels of lobbying success than commonly suggested in the scholarship. In the literature on EU lobbying aspects such as the level of contentiousness over policy alternatives and the diversity of competing policy demands were considered less relevant in characterizing the interest representation system.