This volume contains essays on ellipsis -- the omission of understood words from a sentence -- and the closely related phenomena of gapping. This volume presents work by leading researchers on syntactic, semantic and computational aspects of ellipsis. The chapters bring together a variety of theoretical perspectives and examine a range of cross-linguistic phenomena involving ellipsis in Japanese, Arabic, Hebrew, and in English. This volume will be of interest to syntacticians, semanticists, computational linguists, and cognitive scientists.