Chiquitano/Bésɨro and Guarayo are two communities in Bolivia that share a history of forced migrations and, to this day, face linguistic and cultural erasure. However, they adopted opposite survival strategies: while the Bésɨro embraced European practices, the Guarayo resisted colonial powers and social structures. Today, Guarayo has a healthy speaking community whereas Bésɨro is endangered. Given the vastly different outcomes of comparable historical and colonial impositions, these languages create a natural laboratory for studying the interplay of socio-historical and linguistic factors and their impact on language maintenance. This study blends quantitative and qualitative data collection and ethnographic research to analyze how contact outcomes can be traced to contrasting language attitudes and sociohistorical variables. The urgency for this research increases as Bésɨro’s intergenerational transmission is interrupted, which means that we soon lose this unique chance. By undertaking this research now, this project reveals the diverse and active responses indigenous communities had to colonization, with profound implications for language preservation efforts worldwide. It provides new insights into our approach to language contact in the context of language endangerment, studying the historical consequences of language attitudes, which have never been researched, and bridging the gap between theoretical language contact models and vitality case studies.