Over the last few decades, the Spoken Corpus Linguistics (SCL) has achieved a great deal in terms of quantity and quality of works (O’Keeffe & McCarthy 2010). Enormous progress has been made in the last thirty years and the increment of multimodal corpora stimulates sophisticated investigations on the relationship between the verbal and non-verbal component of spoken communication (Knight 2011). The SCL is a very vital field of research, which is able to provide essential data and tools for the advancement of language knowledge. In this article I will focus on the contribution that SCL and the resulting data provide to general linguistics. In § 2, I discuss the contribution that the SCL gives to a better understanding of linguistic variation; in § 3, I show how the SCL can improve the descriptive adequacy of grammar; finally, § 4 is dedicated to the contribution that speech data can give to a better knowledge of the grammaticality of languages. Across the article I will use mainly data from Italian corpora, but widely validated by comparison with data from corpora of other languages.