This book investigates the acquisition of null and overt subjects at the syntax-discourse interface in second language (L2) Turkish and focuses on first language transfer effects. In the following chapters the book presents the experimental study carried out on advanced and intermediate Japanese Korean English and German L2 Turkish speakers and explains whether discursive constraints residing at the syntax-discourse interface is problematic to acquire as predicted by the Interface Hypothesis in contrast to Full Transfer / Full Access Hypothesis. Framed within the Syntax before Discourse Hypothesis considerations the book also inquires whether syntactic features are acquired earlier than discursive principles regarding the use of null and overt subject distribution.