The development and validation of the Teacher Beliefs Survey (TBS) is described. The TBS, an instrument for assessing the beliefs of teachers related to constructivist and traditional approaches to teaching and learning, contains 21 items in three hypothetical constructs. Elementary teachers, preservice (n = 61) and in-service (n = 137), participated in the development of the TBS. Analysis of this pilot data suggested a four-factor structure: Traditional Management, Traditional Teaching, Constructivist Teaching, and Constructivist Parent. A validation study included preservice teachers (n = 896). The results did not confirm the four-factor structure; further analysis suggested a three-factor structure, eliminating the Constructivist Parent factor. Future plans include development of a Constructivist Management factor and a larger pool of items for existing factors.