The importance of mathematics in early grades has been well established. Two variables that are associated with mathematics achievement are student-teacher relationships (STR) and student type (students identified with a disability and students not identified with a disability). The current study investigated the interaction between perceived STR and student type on mathematics achievement using a nationally representative data set of approximately 8,380 first-grade students, 2,930 teachers, and 860 schools. Multilevel modeling controlling for student-, teacher-, and school-level factors found that both perceived STR and student type were strongly associated with mathematics achievement. There were also two statistically significant moderation effects between close STR and student type on mathematics achievement and conflictual STR and student type on mathematics achievement. This suggests that close or less conflictual STR are beneficial for all students but are especially beneficial for students identified with a disability. Implications for research, policy, and practice are also provided.