The study investigated the effectiveness of a working memory enhancement training program in developing word problem solving skills of fourth grade students with learning disabilities in key stage 1 schools of basic education in Oman. Using a multi-stage sampling, the study sample included initially (40) fourth-grade students from a pool of students referred to learning disabilities units in schools in Al-Seeb, Muscat. The Raven nonverbal intelligence test and a test in word problem solving were administered to the (40) students in order to draw a sample of students with learning disabilities based on the IQ-achievement discrepancy model. Following this, (14) students with mathematical learning disabilities were selected and were randomly assigned to either an experimental or a control group. Both groups were matched and each included (7) students. The students in both groups were administered a battery of test of working memory (visual-spatialexecutive- memory span) and a test in word problem solving in addition to the working memory enhancement training program. Results of the study showed that there were statistically significant differences between the mean ranks of scores obtained by students in the experimental and control groups on the word problem solving total score as well as sub test scores except for counting, and spatial sense in favor of the experimental group. Additionally, there were statistically significant differences between the pre and post scores of students in the experimental group in both the word problem solving test scores and the scores on the memory test battery in favor of the post score test. Similarly, there were statistically significant differences between mean ranks of the experimental and control groups on the memory test battery (verbal- spatial- executive- memory span) in favor of students in the experimental group whereas there were no statistically significant differences in the visual-spatial component. The study recommends the importance of training working memory for students enrolled in mathematical learning disabilities programs in schools as it develops the word problems solving skills.