Research in Second Language Acquisition: Empirical Evidence Across Languages provides an overview of current research within the Processability Theory framework (Pienemann 1998; 2005). The articles in this volume combine a more theoretical approach in order to further extend the theory and studies utilizing PT to further investigate bilingual language acquisition and language development in natural and institutional settings. Taking these different aspects into consideration, this volume is organised in two parts. Part 1 Second Language Processing: Contributions to Theory Development contains a number of papers discussing the inclusion of further theoretical aspects into PT, focusing on English as a second language. In Part 2 Second Language Grammars across Languages, PT is applied to a number of typologically different languages and contexts.