In this chapter, the authors introduce and discuss the approach for defining IT interoperability solutions on national level for social services in Finland. Goals and phases of the national initiative are presented, and various projects related to the transformation and unification of various aspects of supporting social services via interoperability solutions are illustrated. In addition, the path from general e-Government requirements through the definition of domain-specific information and documentation down to the development of technology solutions and dissemination plan is presented. The authors highlight several success factors and issues for the organization of multipartite collaboration, the specification of architectural and information management approach, the selection and definition of technology standards to support the domain-specific information needs and specifications and strategic alternatives for central information repositories.