This paper aims to study Quantifier Floating in English from the viewpoint of principles and parameters theory. It is shown that a floating quantifier is an adverb. This paper further proposes that a covert counterpart of SE-anaphor studied by Reinhart and Reuland (1991) appears as the complement of a floating quantifier. A SE-anaphor must be assigned 0-features by I. In order to satisfy this requirement, a floating quantifier phrase adjoins to the subject. From this, a variety of properties of Quantifier-Floating follow.∗. © 1994, The English Linguistic Society of Japan. All rights reserved.