Alcover gained interest in linguistics departing from folklore, as he noticed a flock of archaic and dialectal words that were not in the local dialect dictionaries. This resulted in the idea of compiling a new dictionary. Moreover, a few years after the death of Marià Aguiló in 1897, Alcover found that the Dictionary of Aguiló was still unpublished. Therefore, it was during those years that the project of the Dictionary was conceived.
In 1900, Alcover drafted the Lletra de Convit (Invitation Letter), which served as a base document for the compilation work of the materials that would constitute the future Dictionary. The first meetings for the preparation of the Dictionary took place in the Episcopal Palace, where he read the Lletra de Convit, a public invitation to cooperate in a comprehensive dictionary of the language. Therefore, the birth of this enterprise was linked to the Church. Alcover focused on linguistic research as a collective endeavour. From the start, he was aware of the unity of the lands from the Catalan Principality, the Roussillon region, the Balearic Islands, the Kingdom of Valencia and the city of Alghero. The project had a big impact. The aim was to compile a dictionary of the Catalan language with all the words, ancient and modern, spoken and written, from all Catalan-speaking countries. Such a purpose was called "a Titan's work": it was hold to be unachievable.
In 1901, a massive gathering was held in the Hall of Bishops at the Episcopal Palace of Mallorca, where the publication of the Bolletí del Diccionari (1901-36) was put forward. This journal was the first philological studies magazine in the state. It became a link between Alcover and his collaborators and correspondents, and it was also used to publish linguistic studies, primarily to instruct the members of the project. In the first volume of the journal, Alcover published Qüestions de llengua i literature Catalanes (Catalan Language and Literature Issues), which gave him great prestige. Later he published Una mica de dialectologia Catalana (Some Catalan Dialectology), which constituted the foundation of the Catalan dialectology in Meyer-Lübke's opinion.
In 1921, Francesc de Borja Moll moved to Mallorca, summoned by Alcover, and he devoted himself to the Dictionary. In fact, the Dictionary was eventually completed by Borja Moll after Alcover's death in 1932.
The masterpiece of Antoni M. Alcover was the great Catalan-Valencian-Balearic Dictionary, an alphabetical lexical inventory of the Catalan language in ten volumes, written by himself and completed by Francesc de Borja Moll. The first volume appeared in instalments between 1926 and 1930, and the second volume was published in 1934, before the civil war (1936). The project resumed in 1950, with the emergence of the third volume. The last one was published in 1962.
Its main peculiarity is that it is a very encompassing work which includes words of both spoken and written language, literary and colloquial, of all ages and from all points of the Catalan-speaking lands. It collects meanings for words that refer to the districts and villages they come from, sayings, phrases, references to folklore and customs, and their Spanish translation. For its size and the quality of research, it is still the largest linguistic enterprise in Romance languages, a unique work in Europe.