The Person-Case Constraint (PCC), a phenomenon restricting pronoun ordering, finds much discussion in the syntactic literature. Cross-linguistically, four different forms of the PCC are possible. That is, there are four different sets of pronoun-case combinations that are permissible across human language in situations where the PCC would apply, with all other combinations of pronoun-case being ungrammatical. Among these paradigms, Spanish has one of the most restrictive. In double object constructions, for instance, it is only possible to have a clitic cluster composed of a first- or second-person indirect object followed by a third-person direct object; all other combinations are ungrammatical. Previous attempts to capture this phenomenon have posited a fundamental limitation on Agree that produces the surface restrictions observed across languages. In the case of Spanish, though, an analysis of child input using the CHILDES database reveals that there are almost no natural-language examples of the PCC being violated, suggesting that a purely syntactic explanation under a principles-parameters learning framework cannot fully account for the phenomenon. Additionally, previous work in Basque suggests that a syntactic solution cannot work across languages. We propose that the PCC is fully learnable through Yang’s Tolerance Principle. This approach does not rule out syntactic or morphological explanations for the PCC; rather, it suggests that the presence of the PCC in Romance languages is trivial and follows from the lack of ungrammatical input to the child.