This article analyses how the administrative-bureaucratic or staff support structures available to Members of the European Parliament (Secretariat officials, political group advisors and parliamentary assistants) changed in response to the formal development of the European Parliament into a legislature or parliamentarisation. Providing a temporal perspective, the aim is to explain bureaucratisation (as the processes whereby non-elected officials carry out elected representatives’ duties and tasks) as it presents in the EP today. Based on interviews and other data, findings show that while changes to administrative-bureaucratic structures have not always been timely to EP’s parliamentarisation, they strengthened the EP’s administrative capacity incrementally. Arguing that administrative and political structures develop differently at given moments and infringe upon another, the article discusses the consequences of staff support for democracy. The analysis shows that the diversity of administrative structures is a source for maintaining democratic control in parliament and limiting bureaucratisation.