Competent L2 writing has been described in research in terms of an increasing incidence, variety, and length of clauses; a countervailing compactness and tightness with reduced number of clauses even as clause length expands; and various interrelationships between syntactic realizations of texts and the genres they represent. These partly contradictory features are typically related to the fact that "advancedness" is both a notoriously vague term and a developmental stage that is more expansive than are introductory and intermediate levels of L2 performance. To contribute to a more differentiated understanding of advancedness--particularly its gradual development in instructed settings--this article examines the characteristics of advanced writing through an analysis of data that are (a) longitudinal, rather than cross-sectional, (b) embedded in an instructional environment that has implemented principled, articulated curricular, and pedagogical practices for the development of advancedness, and (c) analyzed within a systemic-functional linguistic framework in order to focus on the notions of experiential and logical meaning. By analyzing the intraclausal and interclausal resources that evolving advanced learners use and by relating them to the learners' developmental trajectory, this article contributes to a better understanding not only of the nature of advancedness but also of its development by adult instructed learners.