This article attempts to account for the derivation of pronominal clitics in contemporary Western Iranian languages. It argues against the common assumption (detailed in Section I) that all clitics derive from thegenitive/dative ones of Old Iranian and explores the alternative possibility that some clitics in Western Iranian languages may derive from the Old Ir. accusative forms, or may represent a general oblique form resulting from a coalescence of the Old Ir. gen./dat. and acc. clitics (Section II). A derivation from such a general oblique is specifically plausible for the plural clitics in those Western Ir. varieties (discussed in Section III) whose pl. clitics are not derived from the sg. ones. This implies a revision of a morphological isogloss which has posited a certain grouping of the Western Iranian languages on the basis of the distribution of two variants of the 3rd sg. clitic, and suggests a more complex picture (Section IV). Although they do not belong to the Western Iranian group, data from Avestan and Sogdian will be used to broaden the basis for comparison with contemporary Ir. languages.