The theory and tools of "improvement science" have produced performance improvements in many organizational sectors. This essay describes improvement science and explores its potential and challenges within education. Potential contributions include attention to the knowledge-building and motivational systems within schools, strategies for learning from variations in practice, and focus on improvement (rather than on program adoption). Two examples of improvement science in education are examined: the Community College Pathways Networked Improvement Community and lesson study in Japan. To support improvement science use, we need to recognize the different affordances of experimental and improvement science, the varied types of knowledge that can be generalized, the value of practical measurement, and the feasibility of learning across boundaries.