Optimism in conservation, and its potential impact on conservation practice, has been the focus of considerable recent attention. Dispositional optimism is the tendency to have positive expectations for the future, and previous research on optimism has focused particularly on the relationship between optimism and positive health outcomes. This research has concluded that optimism is generally a positive trait that can help people address problems, and set and achieve their goals. These characteristics may also be beneficial in conservation contexts. Using the revised Life Orientation Test, we measure dispositional optimism in conservation professionals to assess whether they are more or less optimistic than individuals who do not work in conservation, and whether there are differences in dispositional optimism between conservation professionals. We find that conservation professionals in the UK are more optimistic than a comparator sample of UK residents. Within conservation professionals, we do not find differences in dispositional optimism with age, gender, country of residence, employer, employment status, whether an individual thinks of themselves as a conservation biologist, or years working in conservation. We find weak evidence for lower dispositional optimism in conservation professionals working in Europe, Africa and South America. The most commonly expressed motivation for working in conservation was a feeling of love or connection, but we found no relationship between motivations and dispositional optimism. We did find that conservation professionals with higher dispositional optimism were more likely to be optimistic about the future of conservation, although no more likely to be optimistic about three specific conservation issues. Greater optimism in conservation professionals has important implications for conservation practice—optimists could benefit the success of the projects they work on, and benefit from the resilience that optimism provides, in a difficult sector where success is uncertain.