The paper investigates nasal epenthesis in vowel-initial preverbal 3rd person accusative pronouns in modern dialectal European Portuguese (EP). The study is underpinned by the data from the verbatim transcription section of CORDIAL-SIN, a dialectal corpus of contemporary EP. Speakers’ behaviors are analyzed in the fifteen localities where variation is found. Different grammars (prosody-syntax mappings) are singled out, depending on whether the alveolar nasal is extended on preverbal clitic pronouns only or is found in other monosyllabic clitic words (definite articles and demonstrative pronouns) as well. Analogical extensions are demonstrated to be instrumental in inducing speakers to use the nasal-initial allomorph. The analysis points also to the varying realizations of proclisis triggers. Besides surfacing as a nasal diphthong, their last syllable frequently ends in a monophthong, its vocalic nucleus denasalizes or its quality gets altered. Finally, the historical profile of this sandhi process is approached. The change is argued to have spread from grammatically and communicatively unmarked contexts, close to orality. Rather than positing a continuous transmission of nasal epenthesis across generations, emphasis is placed on the consistency with which preverbal clitic pronouns were treated in various periods and in different communicative circumstances.