The gap between science and practice has historically been a major topic in the field of conservation biology. In this article, I review this gap at both the international and domestic level, and subsequently discuss what types of scientific knowledge and insight are required to promote practical conservation, particularly in Japan. At the international level, scientific evidence is needed, for instance, to provide a rationale for the Aichi Biodiversity Target and to measure the extent to which the target has been achieved. At the national level, various questions emerge in the practice of policy-making. Furthermore, certain sub-fields dictate what types of scientific information are lacking. To facilitate the development of research that addresses such gaps, I also discuss the scientific information that should be provided by researchers to aid policy-making decisions, as well as how this it should be provided. Furthermore, I discuss how researchers can identify this type of information.