Inflection is present in all Romance languages, even if at times it can be replaced by the use of clitic elements. It is therefore a crucial feature of the language for children to acquire. The acquisition of inflected forms was studied in the nominal, verbal, and adjectival systems because it is present from the very first forms produced by children. Data are presented from the literature for six languages: Portuguese, Spanish, Catalan, French, Italian, and Romanian. For all these languages, there exist open access corpus data available on the CHILDES website, which make it possible to have first-hand access to actual spoken data for these languages. Results show that children produce correct forms very early on for the most frequent grammatical elements (by age 2 for most children, but sometimes as early as age 18 months). This includes the use of nouns and determiners in both genders, and the use of verbs in the present, perfect, and imperative forms. Verbs are produced first in the third person, followed by the other persons. Nouns and verbs are used in the singular form before being used in the plural form. Other more complex grammatical forms, such as, for example, the imperfective past tense or the present conditional, emerge only later, and this is probably related to the semantics of the forms rather than their complexity. In most cases, there is correct agreement between noun and determiner, or verb and personal pronoun, or noun and verb. Errors are infrequent, and the nature of the errors can be used as means to study the mechanisms of language acquisition.