Linguistic complexity is one of the currently most hotly debated notions in linguistics. The essays in this volume address the intricacies of assessing the complexity of languages and language varieties (here: of English) in three major linguistic disciplines: creolistics, indigenization and nativization studies, and Second Language Acquisition research. The volume is thus unique in bringing together leading representatives of three often disjunct fields of linguistic scholarship in which linguistic complexity is seen as a dynamic and inherently variable parameter.