The second DIVERSITAS Open Science Conference (OSC2) took place in Cape Town, South Africa, on 13-16 October 2009. The conference was entirely dedicated to biodiversity science and its connections to policy. It assembled many perspectives from the natural and social sciences to highlight the causes and consequences of biodiversity change, and discuss solutions to the consequences of this change. The DIVERSITAS OSC2 gave particular importance to the role of science in informing policy through the organisation of five science‐policy round tables on the following topics: IPBES, TEEB, ABS, CDB 2010 and agrobiodiversity. This conference attracted an international audience of 700 scientists and policy makers from about 70 countries. About 40% of these participants came from developing countries, and 30% were young scientists. The conference received an important exposure in the media. Altogether, articles were published by more than 300 news organisations/sites in at least 11 languages in 31 countries. DIVERSITAS, through the APN sponsorship, was able to support six participants from developing countries of the Asia‐Pacific region, one of them being a young scientist too. These grantees gave oral or poster presentations at the DIVERSITAS OSC2 and strengthened their international cooperation.