This paper provides the first evidence of maternal speech--motherese--in Wichi, an indigenous language with a complex morphology spoken in the Gran Chaco region of Argentina. The corpus consists of 22 hours of video recordings from the daily life of three children, starting from their one-morpheme utterance period (MLU = 1) to the onset of combining early morphemes (MLU = 2.30). Employing a mixed methodological approach, results allowed us: (a) to create an observational system of specific categories for the analysis of the maternal speech in Wichi; (b) to identify motherese in Wichi, noticeably stable across cases and organized into constellations of lexical, pragmatic-discursive and prosodic features with changes and continuities during the developmental target period. The results are discussed cross-culturally in the light of a renewed cultural approach, while limitations and future directions are addressed. [Translation from Spanish by Jennifer Martin.]