This chapter presents a case study of scaling up the T-STEM initiative in Texas. Data come from the four-year longitudinal evaluation of the Texas High School Project (THSP). The evaluation studied the implementation and impact of T-STEM and the other THSP reforms using a mixed-methods design, including qualitative case studies; principal, teacher, and student surveys; and a quasi-experimental approach to examining the effects of the programs on student achievement and achievement-related behaviors. The chapter presents a brief description of T-STEM characteristics and early outcomes on math and science achievement. It then examines variation in the local interpretation and enactment of the blueprint designed to guide T-STEM academy development. A multidimensional infrastructure supported T-STEM implementation and provided needed technical assistance. Yet T-STEM academies' primary affiliations through their district or external support network provided the strongest context for implementation, shaping priorities and affording resources and know-how. The chapter offers key lessons for policymakers and practitioners engaged in supporting STEM efforts in particular and new school models in general.