Both additive and proportional reasoning are types of quantitative analogical (QA) reasoning. We investigated the development and nature of primary school children's QA reasoning by offering two missing-value word problems to 3rd to 6th graders. In one problem, ratios between given numbers were integer, in the other ratios were non-integer. These word problems were written in the Greek alphabet, and thus totally incomprehensible to the children. QA answers considerably increased with age. Younger children more frequently chose additive relations, whereas older children chose more proportional relations. The nature of the ratios between the given numbers also affected the answers, particularly in 5th grade. [For the complete proceedings, see ED597799.]