In summary, we have developed the first strategy for metathesis of alkyl halides and olefins using diazene catalysis. As with other metathesis chemistries, a number of unique synthetic applications can be envisioned for this type of exchange. We anticipate that further development of this chemistry could arise from the development of diazene catalysts with improved rates of alkylation, cycloaddition, and cycloreversion, and through the identification of alternative electrophiles to give entry to the key hydrazonium intermediate.