In this paper I propose a new analysis of null arguments in Old Norwegian. I argue that the option of null realization in Old Norwegian correlates with a distinction between φ P and DP pronouns in the sense of Déchaine & Wiltschko (2002), and that this distribution can be captured by a version of pronoun deletion (Roberts 2010b). On a more general, theoretical level, I argue that both the structure of pronouns and that of the functional domains C, T and v influence the null argument properties of a language. Thus, null arguments, but also $blocking$ of null arguments in non-null-argument languages like Modern Norwegian and English, may be derived in different ways.