Despite the increasing popularity of studies on teachers' national curriculum adaptations, there is no comparative study elucidating teachers' adaptations in centralized and decentralized educational contexts through sense-making theory lenses. This paper presents a comparative case study of Turkish and Swedish senior classroom teachers' curricular adaptations concerning sense-making theory. We get data through non-participatory lesson observations, interviews, and document analysis from two teachers teaching third-grade mathematics in each country (Izmir and Malmö). Findings reveal that both Turkish and Swedish senior teachers frequently extend, replace/revise and omit the mathematics curriculum. Turkish teachers provided extensive evidence about their adaptations and even tried explaining their reasons whereas Swedish teachers perceived the changes they made in the classroom as teaching rather than adaptations, due to different levels of centralization. Additionally, Turkish teachers responded with parallel structures and assimilation to the national curriculum, and Swedish teachers responded only with assimilation. However, a Turkish teacher's assimilation mediated fewer adaptations while both Swedish teachers' assimilation mediated more adaptations (extension and replacing/revising). We conclude by drawing implications for research on teachers' adaptations and sense-making.