This longitudinal case study examines reading difficulties identified in Grade 2 and Grade 6 national assessment test (NAT) scores in relation to Grade 9 NAT in Swedish (L1) and English (L2). A norm-referenced screening was used in Grade 2 to assess word reading and reading comprehension. In line with the simple view of reading, four subgroups were identified: (1) Typical reading development, (2) Word reading difficulties, (3) Reading comprehension difficulties, and (4) Mixed difficulties. Results indicate that reading difficulties in primary school have long-standing implications for educational attainment in Swedish and English. In logistic regression models students with reading difficulties in Grade 2 and low Grade 6 NAT-scores had a higher probability to achieve low attainment levels in Grade 9. This implies that a norm-referenced screening in Grade 2 can be useful for identifying students at risk of low attainment in language subjects at the end of compulsory school.