Research suggests that the quality of interactions and relationships teachers share with students and students' social skills are interrelated, but it is less clear if this relationship is bidirectional or consistent across elementary school. The purpose of this research study was to estimate the possible longitudinal and reciprocal effects of teacher-student relationship quality (TSRQ) and social skills for kindergarten through third grade students. Longitudinal reciprocal relations between teacher-rated closeness and conflict, and student interpersonal and self-control skills were estimated to examine the strength and direction of associations in a large, nationally representative longitudinal sample (N = 12,507, ECLS-K:2011). Structural equation modeling was used to test a panel model of reciprocal, longitudinal effects of TSRQ and social skills. Main results suggest that the small to moderate effects of teacher-student closeness on student's interpersonal skills are bidirectional ([beta]'s = 0.07 to 0.15). Additionally, the moderate to large effects teacher-student conflict on student's self-control skills are bidirectional ([beta]'s = -0.12 to -0.35). Prior teacher--student conflict also had large negative effects on subsequent interpersonal skills, but not vice versa ([beta]'s = -0.25 to -0.28). Implications of the findings and ways to improve relationship climate and student outcomes are discussed. Impact Statement: The quality of teacher-student relationships and a student's social skills are reciprocally related from kindergarten to third grade, after controlling for differences due to race, gender, and socioeconomic status. Teacher-student closeness and students' interpersonal skills have bidirectional relations. Additionally, teacher-student conflict and students' self-control skills have bidirectional relations.