There are many examples of decision support tools used to analyse information with the intention of assisting conservation managers and policy makers in their decision making. We used structured interviews to collect information on seven case studies from Australia and New Zealand to identify the factors that led to the use (or non-use) of decision support tools when developing conservation policies. The interviews explored hypotheses derived from existing literature on the use of decision support tools in conservation policy. Qualitative analysis of the interviews indicated that key factors influencing the uptake of a decision support tool in conservation policy include the alignment of the tool with the objectives and context of a policy, and its ability to be useful even in the presence of missing data. Two other factors that had been suggested in past literature were not perceived by interviewees to be as important as the above two: the presence of a champion for the decision support tool within the management agency, and the time required to apply the tool. The interviews also revealed a number of additional factors that influenced use or non-use of decision support tools that we had not extracted from existing literature: ambiguity about policy objectives, the autonomy of the agency, and the employee time costs of applying the decision support tool.