This chapter investigates the relationship between morphological complexity and language contact and change across western Amazonia. We explore morphological proliferation in particular domains (nominal classification, tense, evidentiality, and valence-adjusting), and follow this with a more systematic exploration of morphological complexity in relation to wordhood status across a sample of eleven Amazonian languages. We argue that a large percentage of bound morphemes in these languages display ambiguity between morphotactic versus syntactic analyses, suggesting that morphological autonomy is best characterized as a matter of degree, and that different degrees of autonomy may apply on a regional scale. Since many accounts of word-internal morphological complexity implicitly rely on notions of autonomy, Amazonian languages invite a revision of our current conception of this domain.