Research on regulation has focussed on explaining the independence of sector regulators and assessing the effects of regulations on markets. This article broadens the scope of such research by studying and explaining how regulatory actors interact at the de facto level in a multi-actor regulatory arrangement when making regulatory decisions in the telecommunications sector of Colombia. We propose that regulatory decisions depend on the manner in which actors influence each other. In this article, we are not only focussing on the policy outcome itself but also on the regulatory decision-making process. We performed a social network analysis and used an exponential random graph model to analyse the data. Our findings suggest that actors’ level of influence is affected by the access they have to other organisations, the divergence of positions they have with these other organisations and the power resources of an organisation. In addition, there are structural network characteristics that affect regulatory decisionmaking.