Two morphological constructions operate within the broad, functional domain of causation in Northern Paiute (Numic; Uto-Aztecan). One, the instrumental prefix construction, indicates the means or manner by which some action is carried out by characterizing features associated with instruments. Syntactically, like a morphological causative, this results in the addition of an agent to the valence profile in the derivation. Another, the applicative construction, also functions as a morphological causative in the context of a subset of stative intransitive verbs. The distinct pathways of grammaticalization are explored in this paper by proposing a set of communicative-functional pressures, resulting from the loss of an older causative construction, to fill the domain of causation.