Meta-analyses suggest that instructional quality in the classroom and the quality of teacher-student relationships (TSR) predict positive social-emotional and achievement-related outcomes. Psychoanalytic theory asserts that positive teacher-student relationships are particularly important for outcomes in classrooms with more students with severe psychosocial difficulties. Hence, this study tests whether classrooms with more students with severe psychosocial difficulties have better social-emotional and achievement-related outcomes when teachers have been able to establish more positive relationships with their students. Hierarchical linear regression models use nested student survey data from 32 classrooms. Results only partially support the hypothesis and suggest that too many students with psychosocial difficulties might overwhelm even teachers with strong relationship-building skills, leading to detrimental outcomes.