In the Arab region, several assessments are available to evaluate student skills in mathematical computations. However, none of them uses formative evaluation to guide universal screening of struggling learners or students with learning disability (LD). The current study aimed to develop mathematical computation curriculum-based measurement (MC-CBM) for Arab speaking fourth grade students, examine its psychometric properties, test its adequacy for use in an Arab context, namely Oman, determine an adequate time for its administration, and develop performance benchmarks. MC-CBM were administered to 528 fourth grade students. Results indicated that the developed measures were adequate for use in the Arab context. Received operation characteristic (ROC) curve indicated good specificity and sensitivity estimates for the MC-CBM. Performance benchmarks were obtained using the 25th and 75th percentiles. Implications are discussed from a contextual perspective.