There is an increased appreciation of the need for horizon scanning: the identification and assessment of issues that could be serious in the future but have currently attracted little attention. However, a process is lacking to identify appropriate responses by policy makers and practitioners. We thus suggest a process and trial its applicability. Twelve environmental conservation organizations assessed each of 15 previously identified horizon scanning issues for their impact upon their organization and the urgency with which they should consider the issue. They also identified triggers that would result in changes in their scoring of the likely urgency and impact of the issues. This process enables organizations to identify priority issues, identify issues they can ignore until there are further developments, benchmark priorities across organizations and identify cross-organizational priorities that warrant further attention, so providing an agenda for collation of evidence, research and policy development. In this trial the review of responses by other organizations resulted in the upgrading of response by a substantial proportion of organizations for eight of the 15 issues examined. We suggest this approach, with the novel components of collaborative assessment and identification of triggers, could be adopted widely, both within conservation organizations and across a wider range of policy issues.