Timber owners in western Oregon have been concerned about the erosion of price premiums for higher quality grades of Douglas-fir sawlogs over the past decade and the associated impacts on rotation decisions. Time series tests indicate that the ratio of #3 (lower quality) to #2(higher quality) sawlog prices did rise over the 1900-2000 period indicating a trend towards a convergence between the prices. To identify causes of this shift, reduced form equations for Douglas-fir sawlogs with time-varying coefficients were estimated using flexible least squares. Relative changes in reduced-form coefficients between grades suggested that prices of higher quality lumber grades became more important for #3 than #2 logs during this period while lower quality lumber grades became more important for #2. These shifts may have been the result of changes in the distribution of qualities within log grades (input quality) and log grade-specific technical improvement in sawmilling. Counterfactual simulations of log prices without historical trends in the reduces form variables had no impact on the #2-#3 log price relation though some cases did effect the relation of both #2 and #3 with #4 (the lowest grade).