This naturalistic observational study examined teacher-child interactions in a third-grade science classroom. Of interest was the extent to which the quality of teacher-child relationships was associated with various categories of interaction, and students' understanding of science concepts. Teacher-child relationships of an intact class of 17 third-grade students were measured using the Student Teacher Relationship Scale (STRS). A series of science lessons were audio/video recorded, transcribed, and all interaction coded into one of 12 categories. Students' understanding of science concepts was measured using teacher administered pre-, and posttests. The analyses identified gains in students' understanding of the science content, and a positive correlation between teacher-child relationships and the quality and quantity of their classroom interactions. The findings are discussed in terms of the importance of teacher-child relationships in shaping classroom talk and dialogue patterns during science instruction.