Evidence-based approaches are key for underpinning effective conservation practice, but major gaps in the evidence of the effectiveness of interventions limit their use. Conservation practitioners could make major contributions to filling these gaps but often lack the time, funding, or capacity to do so properly. Many funders target the delivery of conservation and can be reluctant to fund primary research. We analysed the literature testing the effectiveness of interventions. Of a sample of 1,265 publications published in 2019 that tested conservation interventions, 96% included academics. Only 21% included conservation practitioners, of which just under half were first or last author. A community of conservation funders and practitioners undertook a series of workshops to explore means of improving the quality and quantity of intervention testing. A survey of the suggested proportion of conservation grants that should be allocated to testing intervention effectiveness showed practitioners tended to prefer larger percentages (median 3-6%) than funders (median 1-3%), but the overlap was considerable. Funders can facilitate the testing of interventions through a range of measures, including welcoming applications that incorporate testing, allocating funds to testing, and providing training and support to deliver testing. The funders represented by the authors of this paper have committed to these actions. Practitioners can contribute by committing to routine testing, benefiting from funding allocated specifically to testing, and establishing processes for testing interventions. The organisations of the practitioner authors have committed to test at least one intervention per year and share findings, regardless of outcome. Currently, practitioners rarely lead the testing of conservation actions. We suggest processes by which both funders and practitioners can make this routine. This will not only improve the effectiveness and cost-efficiency of practice, but also make conservation more attractive to funders.