The present study explores the cross-linguistic differences between Spanish and Italian in the anaphoric interpretation of null subjects and overt pronominal subjects. The availability of null subjects in a language is determined by the parametric settings of its syntax, but their felicitous use as an alternative to overt pronouns depends on contextual conditions affecting how different expressions retrieve their antecedents in the discourse. According to Accessibility Theory, at least some of these principles must have universal validity; however, up to now no experimental research has been carried out with the aim of comparing directly the interpretation of anaphoric dependencies in two typologically similar null subject languages. In this paper, we report the results of two pairs of self-paced reading experiments carried out in Spanish and in Italian. The results show a similar pattern for the resolution of null subjects, as predicted by Accessibility Theory, whereas the resolution of overt pronouns seems to diverge. This suggests that subtle differences restricted to the scope of the overt pronoun yield systematic variation between the two languages.