In November 2004 the Nordic Council of Ministers together with the Nordic countries, Estonia, Latvia, Lithuania and Poland decided to initiate a collaboration by approving an action plan for improved co-operation between the countries concerned in the area of construction and building. The co-operation was decided to take place through the following activities To make market information and information on national regulations accessible to potential actors on the market, To expand the basis of experience and new found knowledge in housing construction, To undertake a comparative analysis of regulations within the building sector intended to serve as a basis for deliberations on possible harmonization, To make it possible to compare competency requirements imposed on certain actors in the building process, and To establish a network for joint research and development on issues relevant to the plan of action. This conclusive report summarizes the work completed over the years 2005-2008, including a final seminar in June, 2009. The report gives a detailed description of the Action plan and the organization of the work as well as a summary of finalized projects. The outcome of the final seminar is also rendered in terms of proposed activities for further cross-border co-operation between the countries concerned.