This study empirically tested the contingency relationship between strategy and structure proposed by Chandler and others with hypotheses linking the probability, timing, and magnitude of changes in one attribute to changes in the other attribute. A dynamic analysis of 262 large firms observed over 28 years generally supported the hypotheses, indicating a reciprocal relationship between strategy and structure. However, our results support the original conception of a hierarchical relationship between the two—strategy is a more important determinant of structure than structure is of strategy.