Applicativization is highly productive in a language like Chichewa. The applicative affix augments the a-structure of a verb by bringing in an additional semantic role, which is most frequently a benefactive, instrument or locative role. We show in this paper that the structure of the word can be represented in the form of a morphology-syntax interface tree, which makes it possible to refer to not only parts of the word but also the levels of representation that are associated with each morpheme. The a-structure is of particular interest, as this is the structure that the applicative and passive affixes alter. More importantly, these morphemes alter the existing a-structure, one that is the result of the interaction between the verb root and any other a-structure-changing morpheme that precedes in morphological form the morpheme in question. With the interface tree, it is possible to make reference to an intermediate a-structure, one that is associated with a particular morpheme on the tree. Morpheme order can thus be accounted for more straight-forwardly.