Recent discussions about the role of science and scientific research in society have emphasized the importance of community input into and participation in scientific endeavours. Community participation has been cast as a necessary social good, and essential for good science. Using the examples of two fields of research in South Africa - disability studies and Aids vaccine development - we argue that the notion of participation needs to be problematised and interrogated. We need to distinguish between three ways of viewing participation: i) participation as a perfomative act in itself; ii) participation as a means whereby scientific research gains credibility; and iii) participation as a pragmatic necessity for certain types of research such as drug or vaccine trials. If we think about participation as multifaceted rather than as an inevitable social good, we are able to develop a more nuanced understanding of the ethical interface between science and communities.