A system of equations for predicting current and future stand volumes and future stand densities for two merchantability classes--merchantable and sawtimber--is presented. The familiar modified Schumacher yield equation was used for the stand volume functions, and a modified form of the Chapman-Richards growth model was used for stand density projection. The procedure for modifying the Chapman-Richards function can be used to derive other functional forms with stand age as a variable. Because some of the equations are intrinsically nonlinear and the residuals are probably both contemporaneously and temporally correlated, joint generalized nonlinear least squares were used to estimate the parameters. The resulting system retains the advantages of a whole stand model while providing better estimates through the use of additional stand density information. Forest Sci. 29:582-591.