The industrial heritage of the Central Baltic countries has caused countless areas with contamination from chemicals and from waste. The contamination is a severe threat and because of that there is a direct need to decrease the risks for environment, human health and economy caused by contaminated sites. Finding solutions is a joint issue for all Central Baltic countries. The environmental status of the Baltic Sea has very high international priority. The BECOSI project's focus area "contaminated sites" will make a positive impact to protect the Baltic Sea from unwanted outflow of contaminations from polluted sites. The Central Baltic countries share the same problem with contaminated sites although the reasons for it differ. Latvia and Estonia deals with the legacy of the Soviet Occupation, which includes military sites and old industrial areas. In Sweden and Finland the forest industry, with paper mills and wood-preserve facilities, has caused contaminated sites that affect the Baltic Sea. The BECOSI project is divided into four Work Packages (WP:s). WP 1 Project management incl dissemination and information, WP 2 More efficient supervision and risk management on contaminated sites, WP 3 Management of contaminated sites in spatial planning and WP 4 Information as a tool in managing contaminated sites. BECOSI concerns three important focus areas to improve the environment and minimize the risks for human health caused by contaminated sites. As the contaminated sites management of investigating and remediating is costly, high quality supervision and enforcement is demanded. WP 2 will increase the knowledge of supervision on contaminated sites and includes supervision and enforcement in reality. WP 3 has a broad range of activities that leads to a more developed and structured way to deal with spatial planning and contaminated sites. Spatial planning has met new challenges when towns and cities have become more compact, and centrally located industrial sites or military sites have been taken into reuse. It is necessary to integrate the approach of environmental, human health and economic risks in the planning process. WP 4 will produce methods on how to inform and communicate about contaminated sites. It’s important to give correct and well balanced information about the risks with contaminated sites to avoid unnecessary worries about health and environment. In this work package it will also be assured that the collaboration that we create in the project will live on after the project has ended. BECOSI will achieve new ideas, guidance and tools to work with contaminated sites in a more pro active way for the CB countries. Achievements: The BECOSI project sought to decrease the environmental, health and economic risks caused by contaminated areas. Together the project partners developed more efficient supervision methods and risk management procedures for contaminated sites. A broad range of activities were carried out, leading to a more developed and structured way of dealing with spatial planning and contaminated sites. A third focus area dealt with developing methods of how to inform and communicate details of contaminated sites.