Background: Janitors are a low-wage, ethnically and linguistically diverse, hard-toreach population of workers with a high burden of occupational injury and illness.Methods: Data from an extensive multimodal (mail, phone, web) survey of janitors in Washington State were analyzed to characterize their working conditions and occupational health experiences. The survey included questions on demographics, work organization and tasks, health and safety topics, and discrimination and harassment. The survey was administered in eight languages.Results: There were 620 complete interviews. The majority completed the survey by mail (62.6%), and in English (85.8%). More than half of responding janitors were female (56.9%), and the mean age was 45 years. Twenty percent reported having a (health-care-provider diagnosed) work-related injury or illness (WRII) in the past twelve months. Women and janitors who were Latino had significantly higher relative risk of WRII. Increased risk was also associated with several work organization factors that may indicate poor working conditions, insufficient sleep, and possible depression. Half of injured janitors did not file workers' compensation (WC) claims.Conclusions: Janitors reported a high percentage of WRII, which exceeded previously published estimates from Washington State. Women and Latino janitors had significantly increased risk of WRII, and janitors' working conditions may influence the unequal distribution of risk. WRII surveillance via WC or medical care usage in janitors and other low-wage occupations may reflect substantial underreporting.Characterizing the nature of janitors' work experience can help identify avenues for prevention, intervention, and policy changes to protect the health and safety of janitors.