Complex syntax production emerges shortly after the emergence of two-word combinations in oral language and continues to develop through the school-age years. This article defines a framework for the analysis of complex syntax in the spontaneous language of preschool- and early school-age children. The purpose of this article is to provide practitioners with an overview of complex syntax that advances their ability to assess and intervene in the preschool- and early school-age years. Supplemental Digital Content provides (a) tables that provide additional detail and explanation on the complex syntax types (available at: http://links.lww.com/TLD/A15, http://links.lww.com/TLD/A16) and (b) practice exercises in classifying complex syntax tokens (available at: http://links.lww.com/TLD/A17).