Questions that are introduced by the wh-element 'why' are special. For instance, in Italian and Spanish, they allow the subject to occur in preverbal position in contrast to other wh-interrogatives. The overall goal of this book is to investigate the syntactic (and discourse) particularities of why-interrogatives in Italian and Spanish. More specifically, based on a parallel corpus study and several experimental studies, the factors that affect subject positioning in why-interrogatives are determined. In Italian, focus plays a determining role, while subject type and the heaviness of the subject affect its position in Spanish. After discussing previous accounts that address the differences between the two languages, an alternative approach is presented that builds on differences in the checking of the extended projection principle. Additionally, the special syntactic position of why is further supported by investigating a so far unnoticed intervening element in the context of why-interrogatives, namely vocatives. Finally, subject positioning in Italian why-interrogatives is examined in heritage bilingualism in order to contribute to the debate on the general vulnerability of the syntax-discourse interface.