Interest groups are often described as transmission belts that connect the preferences of their members with public officials in policymaking processes. Through this linkage, public officials can... Show moreInterest groups are often described as transmission belts that connect the preferences of their members with public officials in policymaking processes. Through this linkage, public officials can obtain relevant information and gain legitimacy from those affected by public policies. However, this important intermediary function is not a straightforward endeavor as interest groups often struggle to reconcile their dual function of representing their members while being politically active. This dissertation unpacks interest groups mobilized at the European Union level and examines how they are organized so as to function as transmission belts. Subsequently, it analyzes the effects of this transmissive role for the level of access and influence obtained by groups in policymaking processes. The findings shed light on the difficult task of groups in balancing member involvement while being politically active and the implications for the legitimacy of our governance systems. Show less