We use the standard Glashow-Salam-Weinberg SU(2)/sub L/ x U(1) electroweak theory to calculate the charge asymmetry expected for lepton-pair production in proton-nucleon collisions at various center-of-mass energies. Specifically, we discuss the prospect of measuring charge asymmetry as a means to determine the electroweak mixing parameter sin/sup 2/theta/sub W/, using a proton-beam energy of around 800 GeV. As motivated by the observation that an additional (nonstandard) gauge boson in a low-energy theory appears naturally in the E/sub 8/ x E/sub 8/ superstring studies, we also adopt an extended SU(2)/sub L/ x U(1) x U(1) electroweak model. To study manifestations of the nonstandard gauge boson, we consider a fixed-target experiment at a few TeV as well as for a proton-antiproton or proton-proton collider experiment in the few-TeV range. In particular, the behavior of charge asymmetry near the standard Z/sup 0/ pole is investigated as a possible means to determine the Z/sup 0/-Z'/sup 0/ mixing parameter sinphi. The possibility of a direct search for the nonstandard gauge boson Z'/sup 0/ at Fermilab Tevatron energies is also briefly discussed.