This dissertation offers a novel account of the syntax of sentence adverbs. The need for a new account is clear from the lack of descriptive coverage and theoretical coherence in current work on adverbial syntax. Descriptively, the majority of work has so far neglected the fact that sentence adverbs behave syntactically like typical focusing adverbs. There has been no coherent and let alone comprehensive syntactic analysis of various focus- sensitive adverbs in generative grammar. The main proposal I make is that sentence adverbs, as well as focusing adverbs in general, are `inflectional affixes writ large'. In other words, sentence adverbs are derived in the same way as inflectional affixes are derived in syntax. In the current Minimalist framework (Chomsky 2000 et seq.), this parallelism implies that both involve the Agree operation. More specifically, I propose that sentence adverbs merge with a verbal or a nominal expression as a result of (i) Match between valued interpretable Mood features (the probe) on C0 and unvalued uninterpretable Mood features (the goal) on a lower functional or lexical head, and (ii) Valuation, where the valued interpretable Mood feature assigns a value to the goal. In order to realize the Valuation, sentence adverbs merge with the lower head that is the locus of the goal, or with the projection of the head, as a result of pied-piping, to some extent similar to the way inflectional affixes are spelled out as affixes in order to realize feature valuation (Chomsky 2001 et seq). This merge operation is `delayed- Merge', since this kind of merge applies after regular set-Merge that involves the head containing the goal. Support for this analysis comes from three sources. First, there is extensive evidence that sentence adverbs behave like C0 elements, although their surface syntactic positions are usually lower. This suggests some kind of syntactic dependency between C0 and lower functional or lexical heads. These preliminary but fundamental facts are discussed in chapter 2. Second, in-depth scrutiny of focus-sensitivity based on the notion of alternatives, and the role focus plays in the syntactic positions of sentence adverbs, provide compelling evidence that sentence adverbs are focus-sensitive adverbs. This property, as discussed in chapter 3, is crucial in determining which constituent enters a syntactic dependency relationship with the C0. Third, based on the Chomsky's (2001 et seq.) current developments of the generative grammar, inflectional affixes are derived by the Agree operation, which include Match, Valuation, and realization of the Valuation. Our treatment of sentence adverbs as `inflectional affixes writ large' is not only compatible with the theory, but also provides further support for it. These issues are discussed in chapter 4. The major consequence of this work is to have shown that the theory of sentence adverbs and focusing adverbs is closely connected with the architecture of grammar in general, including the syntax-morphology interface, the syntax-semantics interface, and the Agree operation. There should be much to be gained if we seriously explore the consequences of our findings for the syntax of various other expressions not currently considered to form a natural class with sentence adverbs and focusing adverbs, such as inflectional affixes and clitics.