We present an experimental study of three school choice mechanisms. The Boston mechanism is influential in practice, while the two alternative mechanisms, the Gale-Shapley and Top Trading Cycles mechanisms, have superior theoretical properties in terms of incentives and efficiency. Consistent with theory, this study indicates a high preference manipulation rate under the Boston mechanism. As a result, efficiency under Boston is significantly lower than that of the two competing mechanisms in the designed environment. However, contrary to theory, Gale-Shapley outperforms the Top Trading Cycles mechanism and generates the highest efficiency. Our results suggest that replacing the Boston mechanism with either Gale-Shapley or Top Trading Cycles mechanism might significantly improve efficiency, however, the efficiency gains are likely to be more profound when parents are educated about the incentive compatibility of these mechanisms.