[en] We examine Drell-Yan μ-pair production and heavy quark pair production, and demonstrate how to implement precise comparisons between the theoretical predictions of QCD and the experimental observables. Specifically, we have dealt with theoretical uncertainties arising from higher order corrections, unknown small-χ behavior, and the unknown gluon distribution. We indicate how the above processes can provide discriminating tests of the theory in the kinematic regimes which will soon be investigated by the Tevatron I and HERA facilities. 8 refs., 6 figs