In light of recent work on syntactic head movement and clitic movement in Phase Theory, this paper argues for a feature-based, head-movement account of argumental object clitics in Spanish. The novelty of the proposal outlined in this paper is the extension of a movement approach to indirect object (IO) clitics, which are commonly regarded in the literature as base-generated verb-agreement morphemes. It is shown that IO clitics, like their DO counterparts, engage in probe/goal relations to value and delete uninterpretable Case features, and, upon Agree, cliticize via head movement. Chomsky’s operation of inheritance (2008) figures in this account, as it helps explain the derived order of clitics in IO-DO clusters in Spanish. This study is the first of its kind in offering a unified movement proposal for both types of argumental object clitics, while at the same time maintaining the simplest ‘Minimalist’ assumption that both are pronouns of the category DP. Finally, the syntactic analysis proposed for the derivation of argumental clusters is applied to derive dialectally-attested strings composed of three members in which the foremost form is a non-argumental SE clitic.