Understiinding arithmetic word problems involves a complex interaction of text comprehension jmd mathematicjd processes. This work presents a com- puter model of the hypothesized processes that are required of a young student solving arithmetic word problems, including the processes of sentence-level reading and text integration. Unlike previous com- puter simuLitions of word problem solving, which neglect the early stages of text processing, this model forces a detailed consideration of the linguistic pro- cess, which is being increasingly recognized as a pri- mary source of difficulty. Experiments were con- ducted to isolate critical text comprehension processes. Children's probability of solution was jinalyzed in regression jinalyses as a function of the model's text comprehension processes. A variable measuring the combined effects of the load on working m e m o r y and text integration inferences accounted for a significant runount of variance across four grade levels (K-3). The results suggest n e w process-oriented measures of determining w h y a particular word problem m a y be difficult, especially for young students. A n implica- tion for education is the potential for a difficulty- differentiated network of problems that includes a multiple number of rewordings for each "traditionjU" problem wording as an iiid for classroom assessment and future computer-based learning environments.