Recent curricula in many countries suggest that children are introduced to chance and probability in early years of schooling. Probability has had various meanings throughout history, most of which are complementary; however their epistemological differences have been a source of philosophical debates and cognitive conflicts. In this paper we analyze the meanings suggested for probability in the primary school Spanish curricular guidelines. Using ideas from the onto-semiotic approach, we identify the mathematical objects (problems, concepts, propositions and procedures) suggested in these curricular documents for different meanings of probability. We finally establish a reference meaning that may be useful to understand and analyze teaching practices, as well as to predict and help overcome children’s possible learning conflicts.