We study the production of single isolated leptons at large transverse
momentum, p(T)l > 1/2 M(W). The dominant source of such leptons is pr
oduction of an on-shell W boson recoiling against a hard jet. Vetoing
this jet forces the W boson to be produced off resonance and significa
ntly reduces the standard model cross section, thereby enhancing the d
iscovery prospects for non standard model physics. A significant numbe
r of events have the topologically interesting signature of a large p(
T) lepton balancing a jet with little measured missing transverse ener
gy.