Experiences of workplace mistreatment are associated with poor physical and mental health outcomes. Workplace mistreatment among early childhood education workers is underexplored in the United States. The National Institute for Occupational Safety and Health’s Worker Well-Being Questionnaire was used to assess the extent and types of workplace mistreatment among 332 early childhood education staff in 42 Head Start centers in Colorado. The authors assessed seven forms of mistreatment, sociodemographic differences in mistreatment, poor mental health days, and the relationship between experiences of mistreatment and mental health. Condescending or demeaning treatment was the most common form of workplace mistreatment (24%) and 15% of respondents reported two or more types of mistreatment. The mean number of self-reported poor mental health days per month was 7.44 days (SD ± 8.51). Younger workers aged 18–29 and 30–44 years reported significantly more poor mental health days than older workers (8.0 and 8.9 vs. 5.6, p < .05). A greater number of different types of workplace mistreatment was positively associated with poor mental health days, controlling for sociodemographic covariates (β = 0.14, p < .05). These findings suggest a need for organizational-level change and additional support structures to help early childhood education workers to thrive, thus ensuring quality education for children in the United States. (author abstract)