For decades, education researchers have been drawing attention to the importance of professional collaboration among teachers as a way to improve student achievement. But not all collaboration is equally effective. Andy Hargreaves and Michael O'Connor explain that the most successful and sustainable efforts are characterized by both solidity and…

Teachers might be working significantly more with one another, but principals are not. Superintendents might bring principals together for district meetings or even to expose their performance results to colleagues in public, but principal collaboration is too often trumped by district control. Even worse, more and more schools and their…