Limits on the lepton-flavor-violating reactions Ze-+Z and Ze++(Z-2), muon-electron and muon-positron conversion, have been obtained from a search performed at TRIUMF using a time-projection chamber. Upper limits (90% C.L.) for the branching ratios compared to ordinary muon capture for a titanium target are Re"(Ti)="(Tie-Ti)/"(Ti capture)<4.6×10-12 and R+(Ti)= "(Tie+Ca*)/"(Ti capture)<.1.7×10-10 A smaller data set obtained using a lead target yielded R-(Pb)<4.9×10-10. The implications of these results for extensions of the standard model which allow lepton-flavor violation are discussed. © 1988 The American Physical Society.