The article explores reading and knowledge development in pupils receiving bilingual instruction in Swedish and Arabic during their first five school years. Attempts are also made to compare their reading level in Arabic and Swedish. Reading development has been documented by assessment materials generally used in schools, complemented with reading-tests in both languages. In addition the pupils’ results on the mandatory national tests assessing goal attainment in primary school years 3 and 5 are presented and compared to the results of Arabic speaking and other multilingual pupils at the same schools, who did not receive bilingual instruction. Findings show that the pupils from the bilingual classes mostly performed at the same level as pupils educated in Swedish only. They were slightly but seldom significantly behind in reading Swedish but many were proficient in reading Arabic as well. Certain differences in performance are discussed but the material does not permit to draw conclusions concerning the consequences of bilingual education. Other factors and circumstances affecting school performance need to be considered.