Some verbs in Romance (e.g. the reflexes of faciō ‘do’, dīcō ‘say’, habeō ‘have’, sapiō ‘know’, possum ‘be able’, and volō ‘want’) display alternations between a short (e.g. It. f‐are, f‐a, d‐ire) and a long (e.g. It. fac‐evo, dic‐e, dic‐evo) stem. This paper contains an exploration of the lexical and paradigmatic distribution of these stem alternations across Romance varieties to trace when they emerged, how and why. The results suggest a comparatively early emergence as a result of the interaction between preexisting morphological predictability relations within the paradigm and an evolutionary preference for shorter forms in high‐frequency word forms and lexemes.