“Infinitival clauses” are constructions with a clausal status whose predicate is an infinitive. Romance infinitive clauses are mostly dependent clauses and can be divided into the following types: argumental infinitival clauses (such as subject and object clauses, the latter also including indirect interrogatives), predicative infinitival clauses, infinitival adjunct clauses, infinitival relative clauses, and nominalized infinitive clauses (with a determiner). More rarely, they appear as independent (main) clauses (root infinitival clauses) of different types, which usually have a marked character.
Whereas infinitival adjunct clauses are generally preceded by prepositions, which can be argued to be outside the infinitival clause proper (i.e., the clause is part of a prepositional phrase), Romance argumental infinitive clauses are often introduced by complementizers that are diachronically derived from prepositions, mostly de/di and a/à. In most Romance languages, the infinitive itself is morphologically marked by an ending containing the morpheme {r} but lacks tense and agreement morphemes. However, some Romance languages have developed an infinitive that can be inflected for subject agreement (which is found in Portuguese, Galician, and Sardinian and also attested in Old Neapolitan).
Romance languages share the property of English and other languages to leave the subject of infinitive clauses unexpressed (subject/object control, arbitrary control, and optional control) and also have raising and accusative-and-infinitive constructions. A special property of many Romance languages is the possibility of overtly expressing a nominative subject in infinitival clauses, mostly in postverbal position. The tense of the infinitive clause is usually interpreted as simultaneous or anterior to that of the matrix clause, but some matrix predicates and infinitive constructions trigger a posteriority/future reading. In addition, some Romance infinitive clauses are susceptible to constraints concerning aspect and modality.