This paper explicates grammatical properties of Extraposition from NP (ExNP) constructions in English in terms of the Phase Theory in Chomsky (2008). We assume that Edge Features (EF) in phase heads can be a driving force for rightward mergers (linearly unrestricted EFs) and transmitted from phase heads to their selecting heads due to the derivationally interpretive mechanism (EF-inheritance). These phase-based assumptions allow extraposed phrases to be adjoined to the rightward position in a single transferred domain where a modification relation can be derivationally formed between relevant phrases and their host DPs. Finally, we show that our approach can be successfully extended to Secondary Predicate (SP) constructions.