This dissertation focuses on Yukuna (ISO 693-3: ycn, Glottocode: yucu1253), an Arawak language of Colombian Amazonia. Yukuna is a definitely endangered, understudied language, spoken by under one thousand speakers in various communities along the Mirití-Paraná River in North Western Amazonia. This dissertation is organized in two parts. Part I provides a grammar sketch of the language (119pp.), on the basis of a first hand corpus of texts (25000 words, 4,5 hours of recording). Part II provides an in depth description and discussion of nominalizations and nominalization based constructions in Yukuna. Nominalizations in Yukuna are pervasive in discourse, and versatile in their functions. Indeed, there are eight different nominalization markers in Yukuna, used with ambiguous verb forms that display both verbal and nominal features. These verb forms are incredibly frequent, found in average in 80% of sentences in the corpus of texts. Verb forms carrying these markers are found in a variety of syntactic positions, and with different functions, from the prototypical referential use of nominalizations as arguments within verbal clauses, to other, less prototypical uses such as in relative clauses, adverbial clauses, clause chaining, and even as TAM and discourse markers in main clauses. Describing the complexity of Yukuna nominalizations in terms of their internal structure, external distribution and corpus frequency represents a major methodological challenge. This dissertation aims to present the complexities of Yukuna nominalizations in a way that is both thorough and systematic. In this study, I adopt a form to function methodology that establishes the prototype of Noun Phrases as the main tool to identify, categorize and describe nominalizations. Individual constructions are described in terms of the degree to which they match or differ from the language specific features of the NP prototype, in terms of both its internal morphosyntax and external distribution. This method is particularly reliable to identify the distributional and functional expansion of nominalizations, by distinguishing the use of verb forms marked with nominalizing morphology in syntantic positions of NPs (nominalization constructions), from their use in syntactic positions that are not those of NPs. I refer to this latter type of use as nominalization based constructions, following Post (2011). The results of this methodology applied to Yukuna show that the versatility of Yukuna nominalizations in fact largely conforms to the patterns of functional expansion of nominalizations reported in the literature. The most salient fact about the Yukuna nominalizations is that so many of the cross linguistically attested uses of nominalizations are simultaneously attested in a single language.