The article documents the complex process of changing Argentina's science curriculum and implementing those changes over the last 15 years. It recounts how reformers tackled the challenges of balancing national (federal) unity in education with local (provincial) autonomy from the political, social and pedagogical points of view. It also analyzes various attempts to improve science education in Argentina from the viewpoint of their relevance to current developments in various areas of scientific knowledge and human action. In Argentina the effort to ensure equal opportunities for learners at the federal level led to a strong emphasis on developing Common Basic Contents (CBC) for both primary and secondary education. These contents were seen as fundamental components of the competencies that students need in a world increasingly driven by science and technology. Meanwhile, however, Argentina lacked adequate and sustainable policies and strategies for teacher education and training, which led to an unexpected complication: while the curriculum development process led to diverse and sometimes quite sophisticated curriculum documents, the actual quality of science teaching in the classroom did not improve significantly, and teachers still felt the need for more support before they could effectively implement the new science curriculum. The article ends by suggesting ways in which various stakeholders can work together intensively to improve science education in Argentina, in a new process that will respond to the current situation.