Flavor changing neutral currents and multileptons in e⁺e^- and v_μN,v_μN

New quarks and new flavor-changing neutral currents give multiple lepton plus hadron final states in e⁺e^-, v_μN, v_μN. 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 v_μN, v_μN are not sensitive to the presence of flavor-changing neutral currents. Much more sensitive are the processes v_μN are ⁺e^-+βand (for charm changing neutral currents) v_μN→e⁺β.