Impact Assessment (IA) intends to collect evidence on the likely impacts of new policies and thereby minimize unwanted side-effects and maximize the benefits to society. Although it is a requirement in the EC and all OECD countries, the scope and methods vary considerably. Governments have invested considerably in research to support the evidence basis of policy making for sustainable development. However, the general picture shows a gap between the proliferation of IA tools from the scientific community and their actual use in the policy process. The FP7 network of excellence LIAISE (www.liaise- noe.eu) is designed to identify the causes for non-use of IA tools and bridge the gaps between researchers with a generally strong orientation towards their (disciplinary) peers and practitioners who tend to focus on their policy domain and policy problems. LIAISE aims at: 1) understanding of the policy process and the resulting needs for IA knowledge and IA tools; 2) description of IA tools and scientific IA expertise in a standardised way; 3) a shared IA toolbox targeted at the needs of both researchers and practitioners; 4) a shared IA research agenda integrating scientific knowledge gaps and the priorities for the development of new IA knowledge that arise from the future policy agenda; and 5) safeguarding the project results beyond the period of project funding, by developing an institutional setting and a business plan that facilitate the extension of the present consortium towards a broad centre of IA expertise with a structural permanence. A lively interaction between the different communities involved, is essential to realize these objectives. The Berlin Conference is an important opportunity to inform external research groups about the LIAISE approach to bridging the gap between science and policy. Their feedback and views on possible next steps in the further integration of the IA research community are highly valued, as well as their interest to become involved in this process.