This thesis attempts to assimilate head movement as far as possible to phrasal movement. In particular, I argue that if we assume that the computational system of natural languages does not discriminate head movement from phrasal movement in terms of locality and the possible mode of operation, a distributional difference between these two types of movement can be explained by the interaction between a locality constraint and an anti-locality constraint to which syntactic movement operations are subject, and crosslinguistic variations in the possibility of what I will call headless XP-movement and headless XP-ellipsis can be reduced to parameters that are responsible for the possible number of specifiers.

For this purpose, this dissertation discusses a number of syntactic phenomena: nominative object constructions in Japanese, long head movement constructions in Slavic and Romance languages, multiple topicalization in Germanic languages, predicate cleft constructions in Hebrew, Polish, Brazilian Portuguese, and Yiddish, remnant VP-fronting constructions in Polish, a difference between VP-ellipsis and pseudo-gapping in English, null object constructions in Hebrew, Tagalog, Russian, European Portuguese, Japanese, Bantu languages, Persian, and Serbo-Croatian, and yes/no reply constructions in Irish and Finnish.