This paper introduces to a special session on nasalization at the XVIth ICPhS. Nasal studies have a long history, at the interface between phonetics and phonology. Nasal processes are best accounted for by considering the phonetic constraints acting on the production and the perception of nasal sounds, as well as the nasal phonological patterns in the worlds languages. Alternately, nasal studies improve our general understanding of phonetic and phonological processes. The three invited papers of the session are presented and discussed in this framework.