In this paper, we examine the referential properties of null and overt subject pronouns in Catalan in the semi-spontaneous production of oral and written narrative texts by three groups of speakers/writers: 9–10 year olds, 12–13 year olds, and 16–17 year olds. We aim at determining whether these two types of pronouns play the same role and to what extent they contribute to anaphora resolution and discourse cohesion, both at an intra- and an inter-sentential level. We concentrate on anaphoric relations expressed by 3rd person pronouns in subject position. Our results show that, at an intra-sentential level, null pronouns normally refer to subject antecedents, mainly in the spoken modality, while overt pronouns refer back to either a subject or a non-subject antecedent. This entails that once a discourse element becomes a discourse topic and is the subject of a sentence, a null pronoun is used. Moreover, a parallel tendency is observed at an inter-sentential and discourse level.