The aim of this research is to provide a principled account of the generation of embedded constructions (called parentheticals) and to implement the results in a natural language generation system. Parenthetical constructions are frequently used in texts written in a good writing style and have an important role in text understanding. We propose a framework to model the rhetorical properties of parentheticals based on a corpus study and develop a unified natural language generation architecture which integrates syntax, semantics, rhetorical and document structure into a complex representation, which can be easily extended to handle parentheticals. .