After an introduction that briefly describes the two studies on which this article is based, we provide background information on Mexico's education system and the sociopolitical context of the country, and we explain relevant issues of this context for education, arising from the transition from an authoritarian to a democratic political system, at the end of the twentieth century and early twenty-first century. Major large-scale assessments in Mexico are then described, as well as other policies looking to improve achievement, and how the way of disseminating the results of assessments was modified during the period under consideration. In the central part of the text, the impact of tests results' dissemination on educational policies and reforms is explored. Our work focuses on identifying the relationship between dissemination of assessments and introduction of other policies for improving educational quality, with information derived from document review and from interviews with key stakeholders.