This dissertation is a case study of the syntax of the left periphery, using exclamatives in English and Japanese. In the first part, I discuss exclamatives in Japanese in detail by focusing on the properties of the exclamative wh-phrases and particles that function as licensors for wh-phrases in exclamatives. We argue that licensing exclamatives involves at least three functional heads: Finite, Focus, and Mood. Especially, the necessity of the Mood head differentiates exclamatives from interrogatives. On the other hand, we claim that having these three functional projections does not type the clause as exclamative, and show that the presence of a wh-phrase of a distinct form is in fact a crucial part of the clause-typing for exclamation. This conclusion supports the claim that clause type should not be directly encoded into syntax as an independent functional category. The second part of dissertation deals with English exclamatives. We show that sluicing is available in English exclamatives, suggesting that focus is playing a role for the availability of sluicing, assuming that both interrogatives and exclamatives involve focus. Another conclusion about English exclamatives is that exclamative wh-clauses are licensed, not by selection, but by being c-commanded by a factive operator or a factive predicate. This goes against the traditional observation; our conclusion is empirically justified based on the observation that it is possible to license exclamative wh-clauses by a non-local licensor. We argue that this property is similar to what has been observed for the aggressively non-D-linked wh-phrases, accounting for the distribution and behavior of those non-standard wh-phrases. Finally, we investigate how Japanese exclamatives are processed by native speakers of Japanese with an on-line self-paced reading study and two off-line sentence fragment completion studies on the processing of wh-exclamative sentences in Japanese. These studies investigate the real-time formation of sentential structures with higher functional categories, and show that the parser immediately engages to build syntactic structures with discourse-oriented higher functional projections before coming across the head, favoring the incremental processing model.