The main objective of this study, which is part of research on language acquisition, is to examine how the acquisition of retroflex consonant sounds /ɻ/ and /͡ʈʂ/ develops in two children, whose ages range from 1 year and 7 months to 5 years and 4 months, learning the chedungun variant of Mapuzungun in the Alto Biobío region. This research is based on a longitudinal group evolution design, which aims to record children’s verbal behavior in their real emission context, as the same parents/caregivers recorded the participants. Among the main results, it is highlighted that the phoneme /͡ʈʂ/ is noted from 1;08.03. As for the phoneme /ɻ/, it is also recorded from 1;08.03 of age, and in the case of PFS, substitution and elision were the most frequent, persisting until 4;10 years of age in both fonemes