Over the past decade capacity building in schools has emerged as one of the most promising school improvement strategies to help all students meet more challenging standards. The press for accountability in public education, most notably anchored in No Child Left Behind (NCLB, 2001) has spawned a wide variety of educational initiatives aimed at improving schools and enhancing student learning outcomes by increasing organizational capacity through professional development. This paper explores ethical considerations for school leaders as they build teacher/organizational capacity through professional development in their schools. To set the context for understanding the intersection of capacity building, professional development, principal leadership, and ethics, the author begins with a brief overview of literature on capacity building. Next, he describes multiple roles principals take on to create and sustain productive and ethical environments for professional development and work. In the final section, the author uses Starratt's (2004) three ethical leadership virtues--"responsibility, authenticity," and "presence"--first, to examine the intersection of professional development, capacity building, and leadership and second, to propose that school leaders need to be ethical architects as they work to build teacher capacity, improve student learning outcomes, and transform their schools.