Despite English being traditionally classified as a non-null subject language, there are certain discourse contexts in which subject pronouns may be left non-overt. While previous analyses of this phenomenon have focused on syntactic explanations, each has acknowledged that pragmatics plays a vital role in understanding their production and interpretation. This paper takes up where the syntactic analyses leave off, and offers an analysis of the pragmatic motivation behind null subjects in non-null subject languages, focusing particularly on English.It is argued that, far from being exceptional, pragmatically motivated null subjects are not surprising on a relevance-theoretic approach to utterance production and interpretation (Sperber & Wilson, 1986/95). Three categories of null subject are identified, each driven by the balance between hearer's effort and cognitive effects, while allowing for the speaker's abilities and preferences. It is argued that pronouns encode procedural information which guides the hearer to the intended subject referent. Furthermore, the analysis of the discourse contexts in which these subjects may be optionally omitted sheds light not only on the nature of the pronouns themselves, but on the nature of the utterance interpretation process generally, and has important implications for the study of style.