This paper deals with the morpho-phonology of Italo-Romance clitic clusters. It argues that morpho-phonological processes (i.e. apocope, prosthesis, etc.) are sensitive to both the syntactic make-up of clitic clusters and their prosodic structure. The first part of the paper aims to support the hypothesis that a clitic cluster is a Foot, daughter to a recursive Prosodic Word (Peperkamp 1995, 1996, 1997). The second part of the paper accounts for the distribution of the apocopated clitic l (< lo 'it/him'/'the.m.sg') in early Italo-Romance. I show that the distribution of l follows from syllabic and alignment constraints compatible with the foot-based analysis. The last section addresses a puzzling vowel alternation which targets the leftmost clitic of certain clusters in Old and Modern Italian.