Government conservation measures will always depend on public support. While more has been learnt about which species the public values and which conservation measures are socially acceptable, less is known about the criteria that the public thinks government should consider when making conservation investment decisions. This study uses a stated preference best-worst scaling method to gauge the views of a sample of the Australian public on what they think government should consider when allocating funding to threatened species conservation. We found that the three most important factors were the risk that a species might become extinct, the likelihood that a conservation intervention might be effective and the risk of unintended consequences for other species that could potentially arise if the measure was implemented. Costs of conservation measures and the degree to which the society accepts these costs were considered much less important. The latter aspect was consistent with the high level of trust that respondents placed in the judgement of experts and scientists concerning threatened species conservation. We conclude that the Australian Government has a societal mandate to spend more money on threatened species conservation, provided that there is little risk and that it is backed up by science.