This study utilised a cross-sectional survey of 369 participants in 77 countries to examine 15 possible risk and protective factors pertaining to the mental health of aid workers-many of which have not been assessed before-in the categories of job context, working conditions, and demographics. Risk factors associated with job context include emergency postings and being an international worker. No significant differences were found between humanitarian and development workers and none between organisation type; the number of past traumas was not associated with negative mental health outcomes. Protective factors with regard to working conditions include higher income, long-term contracts, previous psychosocial training, and voluntary postings. With respect to demographics, protective factors include older age, more work experience, and greater religiosity and spirituality, while female gender was a risk factor. Ultimately, this study provides a more nuanced understanding of the aid worker sector, which can inform the development of more targeted mental health support.