It has been widely accepted that English object extraposition can be easily accounted for. However, recent research exhibits the fact that various cases of English object extraposition lead to many empirical and theoretical problems in generative grammar. To account for such cases, the previous lexical constraint-based analyses including Kim & Sag (2006, 2007) and Kim (2008) attempt to give an explanation on the phenomenon. They, however, seem to be unsuccessful in providing an appropriate analysis of object extraposition, mainly due to the mistaken data generalizations. Unlike the previous analyses, we claim that all verbs selecting CP objects allow object extraposition and propose a unified constraint-based analysis for the various cases of the construction. Further, it is shown that as a consequence, this analysis of object extraposition can be naturally extended to subject extraposition. Hence, this unified analysis enables us to further suggest that all verbs selecting CP allow subject and object extraposition in English.