The paper provides a state of the art in research on prepositional adverbials in Romance that combine a preposition with an adjective, e.g., Sp. en breve ‘in short’ (= PA-pattern). It therefore reviews the existing bibliography on Romance in general, Latin, Catalan, French, Italian, Portuguese, Romanian, and Spanish. The theoretical background is the hypothesis that the PA-pattern could have played a relevant role as a third way of forming adverbials in the diachrony of Romance, paralleling adverbial adjectives (e.g., breve used as an adverb: hablar breve) and derived adverbs (e.g., brevemente). The review confirms that the PA-pattern is marginal in (written) Latin but rises abruptly in early Romance, suggesting a “hidden” past in spoken Latin. This is corroborated by the fact that similar PA-patterns are used in all Romance languages. However, these insights have often to be deduced from marginal observations on the adverbials in use. As yet, research has not systematically studied the role of PA adverbials in the diachrony of Romance.