The definition of an activity as a “Service of General Interest” influences who and how may provide it. The competence to determine which activities are of general interest lies with the Member States, while the Commission’s task is to watch for “manifest errors” in their assessment. However, it is unclear what the Commission’s competence actually encompasses. This article discusses the scope and limits of the powers of the Member States and the Commission, focusing on legislation, policy documents and case law. It also puts under scrutiny a possible trend of ever more activities being labelled as having an economic nature, as well as the pervasive effects such a trend could have on the Member States' liberty in the “Make-or-Buy” decision.