This is the first in-depth historical treatment of the grammar of the Neapolitan dialect, providing an exhaustive documentation and description of all aspects of the phonology, morphology and syntax of the dialect (and neighbouring varieties spoken in and around the Bay of Naples) which is comprehensive enough to qualify as a reference grammar, but is formulated within a conceptual framework which allows individual facts to be studied as part of a coherent system and compared with other Romance languages. In this respect, it makes a significant contribution towards cataloguing the linguistic typology of dialects within the Italian peninsula.