Mathematics textbooks are a predominant resource in primary school in Greece, as well as in many other countries. The present study reports on both a content analysis of Greek mathematics textbooks with regard to the types of word problems represented in them and a quantitative analysis of children's achievement in these problems. For the purpose of the study, mathematics textbooks of the first two primary school years were analysed using van de Walle's model (1998) of addition and subtraction and a total of 80 children from Grade A and Grade B were asked to solve addition and subtraction problems of the eleven types as determined by the model. The data from the analysis of school mathematics textbooks indicated that there was an emphasis on certain types of problems and a minimal representation of others. Children from both grades were found to perform better on problems that were overrepresented in the school textbooks than on problems with little or no representation. Our findings raise awareness of problems that need to be addressed in mathematics textbooks when dealing with addition and subtraction in order to build children's complete understanding of additive situations. Implications of the role that mathematics textbooks may play on children's mathematical understanding are considered.