The literature on lobbying contains ample evidence how parliamentary committees serve as an important venue for the interaction between external interests and party politicians. At the same time, we have little systematic overview of the contacts between parliamentary committee members and external actors and the factors that determine them. Therefore, we develop a theory predicting the composition of external actor contacts based on overall patterns of state society structures, selection procedures for involving external interests and committee agendas. Our theory is tested on a new original dataset of more than 20,000 individual contacts between external actors and parliamentary party politicians in Denmark, the Netherlands and the United Kingdom during a one year period. Our findings indicate that explanatory factors at all three levels account for a substantial share of the variation in the contacts committee members have with their external constituencies.
