This article describes Project Breakthrough, federally funded as a demonstration through the Javits Gifted and Talented Education Act. Project staff worked for 3 years with three elementary schools in South Carolina to train teachers in the use of language arts and science curriculum developed by the Center for Gifted Education at the College of William and Mary. Teachers implemented the William and Mary units and several of the teaching models used in the units with all students. Goals included (a) improved performance of low-, average-, and high-achieving students in mathematics, science, and language arts; and (b) identification of more low-income gifted students. The article reports on the nature of the project, its implementation, and the results that point to changes in teachers' perceptions of students' abilities and of improved student achievement.