As multimedia and technological savvy continue to expand existing notions of contemporary literacy, the need to prepare teachers to use a variety of classroom technologies has never been greater (Author1 & Author2, 2008a; Author1 & Author2, 2009). In order for teachers to be prepared to use such technologies, the structure of teacher professional development (TPD) is critical. The Teaching Using Technology Studio was designed as a design-based professional development program for sixteen upper elementary teachers in California. This study addressed the following question: What is the impact of a design-based TPD model on teachers' knowledge, attitudes and behaviors regarding integration of technology into teaching and learning? The impact of the program on knowledge, attitudes, and behaviors was measured using pre-post scores on a Knowledge/Use scale, a Teacher Technology Proficiency Assessment, teacher reflections, classroom observations, and student technology proficiency data. Data analysis showed significant changes in teachers reported knowledge and integration of technology into teaching, an increase in technology literacy of teachers and students, and students' use of technology for learning. Findings suggest that TPD models that utilize a design-based approach may hold greater promise for authentic, generative teacher knowledge development and integration of technology into teaching and learning. (Contains 3 tables and 1 figure.)