Eulàlia Bonet the Person-Case constraint (PCC). This constraint, claimed there to be universal, is present in languages that have pronominal clitics, like the Romance languages, languages with weakened pronouns, like English, and languages that have a rich agreement system, like Southern Tiwa. The constraint, thus, affects complexes of ϕ-features related to the argumental structure of the verb. The most common context for the Person-Case Constraint is ditransitive clauses, even though other constructions that can trigger it are causative constructions, and constructions with datives of inalienable possession, for instance. In (1) the effects of the Person-Case Constraint are shown with a first person clitic corresponding to the Direct Object, but ungrammaticality would also arise with a second person clitic (singular or plural). Combinations of two third person clitics do not usually lead to ungrammaticality, even though they often trigger changes not relevant here. The judgements on combinations of first and second person clitics, illustrated in (4), seem to vary a lot. In some languages, these combinations are ungrammatical, while in others, like Catalan, they are grammatical for some speakers, and plainly ungrammatical for others. An additional set of speakers of Catalan accept them in only one of the possible readings, but the judgements as to which one is preferrable seem to vary from speaker to speaker. 3,4 (4) (*) Te m' ha recomanat la Mireia 2Sg 1Sg has recommended the Mireia a. 'Mireia has recommended me to you' b. 'Mireia has recommended you to me' This difference in behavior led Bonet (1991) to posit a strong version of the constraint, for speakers who do not accept sentences like (4), and a weak version of it, for speakers who do accept such combinations. These two versions were stated as follows ((5) corresponds to Bonet 1991: 182, (11)). (5) *Me lui / I-II Constraint a. STRONG VERSION: the direct object has to be third person b. WEAK VERSION: if there is a third person it has to be the direct object