The platform of this master thesis is an interest in sustainable urban development and public-private partnerships in urban conversion. Development agreements in Norway, which are formal partnerships between public and private sector, are being used to a large degree. Both players regard this agreement as a means of implementation, which speeds up the realization of projects in urban development. What is special about this development agreement is that the municipality can impose the private developer to contribute to technical and social infrastructures. With focus on the greater co-operation between public and private sector, this thesis will investigate legal and other sets of problems which will occur in Denmark if a similar type of agreement is to be used that calls for the private sector to contribute to technical and social infrastructures of urban development