To address the challenge of ensuring the quality of preparation of secondary mathematics and science teachers, this article describes the efforts of the "Academy for Teacher Excellence" (ATE; Flores et al., 2007), which received Transition to Teaching grants to establish the Accelerated Teacher Education Program (ATEP). ATEP's purpose was to prepare ethnic minority teachers, mid-career professionals, and recent graduates to become highly qualified culturally efficacious mathematics and science teachers of ELs in high-need schools. Findings from ATEP are unpacked to: (a) analyze mathematics and science teachers' efficacy beliefs, (b) explore the relationship between efficacy sources and the cultivation of mathematics and science teachers' teaching efficacy with ELs, and (c) contemplate practice and research implications for the design of culturally efficacious teacher preparation. The authors report their mixed methods analyses revealed that program and school-context experiences work in tandem to support mathematics and science teachers' efficacy in working with ELs.