A growing literature argues for evidence-based conservation. This concept reflects a wider approach to policy-making and follows thinking in medicine, in which rigorous, objective analysis of evidence has contributed to widespread improvements in medical outcomes. Clearly, conservation decisions should be informed by the best information available. However, we identify issues relating to the type and sources of evidence commonly used and the way evidence-based conservation studies frame policy debate. In this paper we discuss two issues; firstly, we ask 'what counts as evidence?' (what is meant by evidence, and what kind of evidence is given credibility). We conclude that evidence-based conservation should adopt a broad definition of evidence to give meaningful space for qualitative data, and local and indigenous knowledge. Secondly, we ask 'how does evidence count?' (the relationship between evidence and the policy-making process). We conclude that there should be greater recognition that policy-making is a complex and messy process, and that the role of evidence in policy making can never be neutral. In the light of these issues we suggest some changes to build on developing practice under the title evidence-informed conservation. The change in terminology is subtle, yet it has profound implications in that it calls for a re-positioning and re-understanding of conservation science as one source of information among many for decision-makers.