ZhaoHong Han is Professor of Language and Education at Teachers College, Columbia University. Her research interests include second language learnability, second language teachability, and their interface. Among her recent publications are Complexity Theory and Language Development (co-edited with Lourdes Ortega, John Benjamins, 2017), Studies in Second Language Acquisition of Chinese (Multilingual Matters, 2014) and Linguistic Relativity in SLA (co-edited with Teresa Cadierno, Multilingual Matters, 2010).

This volume sheds empirical light on Complex Dynamic Systems Theory by providing analyses of two longitudinal, interactional datasets. The individual analyses traverse the domains of morphosyntax, semantics, pragmatics and discourse. As a whole, the collection demonstrates the impact of the ecosystem on individuals' use of language.