In this paper we investigate V-V incorporation in agglutinating SOV languages as a case of complex predicates involving affixal light verbs that attach to the verbal root they take as complements. The Uto-Aztecan language Hiaki offers excellent evidence of such a phenomenon. We argue that all affixal verb combinations in this language involve VP complementation in support of Wurmbrand’s (2007) analysis of complex predicates and that they are syntactically transparent in the sense of Wurmbrand (2001). That is, they invariably take vP phases (in the sense of Legate 2003) as their complements, which explains both the syntactic and morphological characteristics of the complement clause. These V-V combinations are contrasted with opacity-inducing (CP embedding) complement clauses available in this language, incidentally involving the heavy version of some verbs appearing in the V-V constructions. Finally, we offer evidence that all suffixes participating in complex predicates in Hiaki are affixal light verbs, as defined in Butt (1993), and not auxiliaries or serial verbs, shedding more light on the distinction among these classes.