Zoo educators are important communicators of the targets in education for sustainable development and therefore carry great responsibility for global environmental change. However, German zoo educators form a heterogeneous group, many of them working in non-permanent job positions and facing multiple challenges at work. Applying the job demands-resources model, our study aims at revealing factors influencing zoo educators' job strain. Our data from eight in-depth interviews with German zoo educators confirm that they perceive common factors known from other studies, such as demands (e.g. workload) and resources (e.g. supervisory support). Besides this, job-specific factors were identified (e.g. working with humans and animals). The demands zoo educators mentioned could be classified either as job hindrances (e.g. lack of equipment) or job challenges (e.g. learning). Future studies should quantify these results to facilitate the development of appropriate measures to reduce educators' job strain, thus enhancing their performance.