Teacher emotional wellbeing can exert a strong influence over the ability to effectively perform important aspects of the job, including fostering healthy teacher-student relationships. Our investigation explores one understudied aspect of teacher wellbeing, the presence of secondary traumatic stress (STS). Across helping professions, STS has been associated with a range of emotional and occupational impairments, including difficulty connecting with others (Clunies-Ross et al. in Educ Psychol 28:693-710, 2008). The primary goal of the current study was to determine whether teacher STS influences student socio-emotional functioning through its effects on teacher-student relationship quality. This study was conducted with 150 educators (79% Female, 63% White, 32% Black) and 610 students (59% Female, 91% Black, 1% White) across six urban, public, charter schools in the Gulf South. Results from multi-level structural equation modeling indicated that, as hypothesized, teacher STS symptoms were positively associated with their ratings of students' socio-emotional difficulties ([beta] = 0.28, p < 0.01) such that as teacher symptomology increased, so did the level of student difficulties reported. Contrary to the hypothesis, teacher reports of relationship quality with students were not found to mediate this relationship. Teacher-student relationship quality was negatively associated with their ratings of student socio-emotional difficulties ([beta] = - 0.30, p < 0.01). As teacher reports of relationships improved, their ratings of socio-emotional difficulties decreased. These findings highlight the importance of efforts to identify the prevalence and impact of STS among teachers and the associated outcomes for students. Additionally, results can inform efforts to train and support educators as they work to build relationships with students and foster student socio-emotional functioning.