Allylation and vinylation of aryl radicals generated from aryl diazonium salts provides rapid and efficientaccess to chlorinated and brominated derivatives of styrene and allylbenzene. Allyl chlorides were foundto be better substrates than bromides due to decreased halogen transfer. Donor- and acceptor-substituteddiazonium salts are well tolerated. The products represent important precursors for numerous furthertransformations.