Dallas S. Batten and Daniel L. Thornton engage in a detailed re-estimation of the nature of the impact of money growth and government expenditures in the well-known St. Louis equation. The major purpose of the study is to determine whether the conclusions drawn from previous estimations of this equation depend on the selection of lag length or the imposition of polynomial restrictions. In conducting this examination, the authors generalize a procedure for selecting the lag length and polynomial degree that is both convenient and computationally efficient. They find that the St. Louis equation’s policy conclusions are unaffected by the lag length selected or the polynomial restrictions imposed. In particular, the long-run effectiveness of money growth on nominal spending growth and the long-run ineffectiveness of the growth in government spending are substantiated. Their investigation also identifies a different specification of the equation that outperforms the currently used St. Louis equation in terms of both in-sample and out-of-sample criteria. This new specification has substantially longer lags for both money and government spending growth and more polynomial restrictions than the currently specified St. Louis equation.