Swedish healthcare has undergone continuous development over several decades. Today, legal responsibility is shared on the local and regional levels, i.e. between municipalities and county councils. The purpose of the present study is to gain a deeper understanding of boundary spanning roles and strategies involved in municipal and county council collaboration. A grounded theory approach was used. Fifteen informants from several Swedish health care authorities were interviewed. A tension exists between preserving boundary strategies that stifle collaboration and boundary spanning strategies that facilitate it. The way boundary spanners manage their role is assumed to influence the centre of gravity for this tension and thus the combination of favourable boundary spanning strategies and favourable boundary spanning roles is one way of getting the current form of collaboration to work.