A hallmark of successful communication is the ability to interpret and constrain the range of possible meanings in language discourse. In doing so, speakers consult a range of resources (e.g., syntactic, semantic, lexical) in order to resolve anaphoric dependencies. One such case where speakers consult prior linguistic knowledge is the interpretation of pronominal subjects. There is a growing body of research showing that languages which show optionality with regards to pronominal subjects (i.e., overtly realized or phonologically null) have intrinsically different interpretation biases (Alexiadou & Anagnostopulou, 1998; Sorace & Filiaci 2006; Sorace & Serratrice 2009; Tsimpli, Sorace, Heycock & Filiaci 2004). Using a self-paced reading paradigm, this study explores the interpretation biases of native Arabic speakers (n=38) for overt and null subjects. The results suggest an asymmetric relationship between the two types of pronouns where their distribution is governed by syntactic and processing constraints. Furthermore, the results of this study indicate that the penalty for violating speakers’ prior linguistic biases is stronger for the null and subject position, suggesting that Arabic speakers are sensitive to both type and locality of the pronoun. The results are discussed in light of a representational account underlying the parametric differences in the pronominal system.