The study addresses how recent reforms of the Sickness Benefit Act in Denmark are put into practice. A single case study embedded with five subunits of analysis based on "real life" cases has been conducted in a Danish municipality. Five "sick-listed" citizens and their respective municipal case manager and general practitioner (GP) were interviewed. Two key persons within the municipality were interviewed as background informants. The GPs and case managers ability to co-operate was hampered by lack of time, frequent staff turnover, lack of financial resources, and low accessibility. The motivation for co-operation was low due to low status of social medical issues, lack of feedback and lack of trust. The co-operation was characterized by sequential task integration. The stakeholders encountered difficulties when reciprocal task integration was needed. The decision making was affected by legal constraints and conflicting paradigms of key stakeholders. Rather than forcing co-operation, policymakers should increase the stakeholders' abilities and improve the conditions that create the low level of trust and hamper the willingness to co-operate.