Borrowing, or diffusion, of grammatical categories in language contact is not a unitary process. In the linguistic area of the Vaupés in northwest Amazonia, several different mechanisms help create new contact-induced morphology. Languages which are in continuous contact belong to the genetically unrelated East-Tucanoan and Arawak families. There is a strong cultural inhibition against borrowing forms of any sort (grammatical or lexical). Language contact in the multilingual Vaupés linguistic area has resulted in the development of similar – though far from identical – grammatical structures. In Tariana, an Arawak language spoken in the area, reanalysis and reinterpretation of existing categories takes place when diffusion involves restructuring a pre-existing category for which there is a slot in the structure, such as case. A new grammatical category with no pre-existing slots may evolve via grammaticalization of a free morpheme – this is how aspect and aktionsart marking was developed. The development of a five-term tense-evidentiality paradigm involves a combination of strategies: reanalysis with reinterpretation accounts for the obligatory tense marking, and the history of visual, inferred and reported evidentials. The nonvisual evidential evolved via grammaticalization of a lexical verb while the most recent, assumed, evidential involves reanalysis and reinterpretation of an aspect marker and grammatical accommodation.