This study investigates Chinese and U.S. teachers' cultural beliefs concerning effective mathematics teaching from the teachers' perspectives. Although sharing some common beliefs, the two groups of teachers think differently about both mathematics understanding and the features of effective teaching. The sample of U.S. teachers put more emphasis on student understanding "with" concrete examples, and the sample of Chinese teachers put more emphasis on abstract reasoning "after" using concrete examples. The U.S. teachers highlight a teacher's abilities to facilitate student participation, manage the classroom and have a sense of humor, while the Chinese teachers emphasize a teacher's solid mathematics knowledge and careful study of textbooks. Both groups of teachers agree that memorization and understanding cannot be separated. However, for the U.S. teachers, memorization comes after understanding, but for Chinese teachers, memorization can come before understanding. These differences of teachers' beliefs are discussed in a cultural context.