This paper presents a comparative analysis of three milestone lexicographic works in Ilocano – Carro’s (1888) Vocabulario Iloco-Español, which is translated, augmented and revised by Vanoverbergh (1956); Rubino’s (2000) Ilocano Dictionary and Grammar; and Constantino’s (1971) Ilokano Dictionary. Looking at the dictionary not only as a list of the lexical items used in a language, but as a description of how the language is actually used by its speakers, the study aims to trace the development that Ilocano has undergone through the decades by presenting a review of each of the lexicographic works mentioned above. Ilocano is the third major language in the Philippines, in terms of number of speakers. It is considered as the lingua franca of the north and has been seen as flourishing up to this day, with the proliferation of literature, publication, and agencies that analyze, regulate, and discuss the language. With these in mind, it is deemed important to provide a suitable linguistic work such as grammars and dictionaries, with implications for dialectological study, language pedagogy and translation. Hence this paper attempts to contribute to the scholarly description of the linguistics of Ilocano – from the phonology, morphosyntax, semantics, lexicology, up to language use and socio- and ethnolinguistics, by tackling the processes involved in the compilation of the three dictionaries published.