This study highlights the connections between two facets of teachers' skills--those supporting teachers' mathematical instructional interactions and those underlying social interactions within the classroom. The impact of the Responsive Classroom (RC) approach and use of RC practices on the use of standards-based mathematics teaching practices was investigated in third-grade classrooms. Eighty-eight third-grade teachers from 24 elementary schools in a large suburban district were selected from a sample of teachers participating in a larger randomized-control study. Results showed that teachers at schools assigned randomly to receive training in the RC approach showed higher use of standards-based mathematics teaching practices than teachers in control schools. These findings were supported by analyses using fidelity of implementation: greater adherence to the intervention predicted the use of more standards-based mathematics teaching practices. Findings support the use of the RC approach for creating classroom social environments that facilitate standards-based mathematical practices. (Contains 3 tables and 1 note.)