The purpose of this quantitative correlational study was to examine if, and to what degree, workplace bullying relates to teachers’ stress and depression in the United States. All variables were measured using the Negative Acts Questionnaire-Revised (NAQ-R), Perceived Stress Scale (PSS) and the Patient Health Questionnaire-9 (PHQ-9). A convenience sampling method was used to collect data from the target population of public school teachers. The final sample contained 182 participants. Based on the Heinz Leymann model of workplace bullying, Cognitive Activation Theory of Stress, and Beck’s Cognitive Theory of Depression, this study answered four research questions. The multiple linear regression analysis addressed two research questions. The results revealed workplace bullying (β = 0.30, t = 4.27, p < .001) and perceived stress (β = 0.40, t = 5.63, p < .001), were significant, collective positive predictors of depression. The results also revealed workplace bullying (β = 0.44, t = 6.86, p < .001) and depression (β = 0.34, t = 5.34, p < .001), were significant, collective positive predictors of perceived stress. The Pearson correlation analysis was performed to addressed research questions three and four. The results revealed there was a significant, strong, positive relationship between workplace bullying and teachers’ stress, r (180) = .578, p < .001, two-tailed. The results also revealed there was a significant, strong, positive relationship between workplace bullying and teachers’ depression, r (180) = .536, p < .001, two-tailed. The findings may be used in the development of programs and policies to reduce stress, depression and address bullying behaviors in the workplace.