A solid idea coupled with savvy marketing has enabled Rick DuFour's vision of professional learning communities to revolutionize how teachers work with each other. The author of 13 books and 80 articles has presented to an estimated quarter million educators over the last eight years and is beginning to reach beyond the U.S. with books and presentations. DuFour's approach to PLCs includes collaboration among teachers, work on developing common formative assessments, learning from the results of those assessments, and developing responses and interventions that serve students.