Partnerships are heralded as a key component in threatened species conservation, though their effectiveness has never been quantified. We investigated collaborative processes and identified how they improve conservation outcomes. We conducted interviews with parters from 24 partnerships focused on 23 threatened species or ecological communities. We describe the aims and benefits of the partnerships as well as common challenges to overcome. We outline the key components of successful partnerships, which circumstances are likely to lead to effective outcomes, and the roles that partners play in threatened species recovery. This study can help practitioners developing programs for threatened species recovery, as well as agencies, governments and conservation organisations, and land managers who are invested in threatened species conservation.