Stevens and related rearrangements are reactions that involve the formation of ammonium, sulfonium, and oxonium ylide intermediates and then migrations of activated alkyl groups from the onium heteroatoms to the nucleophilic ylide carbons. After a section detailing possible mechanisms, this review will survey the recent advances that have occurred in the last twenty years in the fields of [1,2]-Stevens, [2,3]-Stevens, and Sommelet–Hauser rearrangements of ammonium and sulfonium ylides.