New quarks and new flavor-changing neutral currents give multiple lepton plus hadron final states in e+e-, vμN, vμN. We observe that (i) e+e- is a favored place to search for their effects through inclusive ratios σ(e+e-+x:σ (μ+μ- +x): σ(e±μ±+x) and same sign leptons e±e±+x, μ±μ±+x,e±μ±+x. Above a new flavor threshold four charged lrpton final states may become important. (ii) Trilepton final states in vμN, vμN are not sensitive to the presence of flavor-changing neutral currents. Much more sensitive are the processes vμN are +e-+βand (for charm changing neutral currents) vμN→e+β.