This paper addresses the identification of pupils with special educational needs (SEN) in mainstream primary schools by their teachers. Data were analysed from two consecutive measurement occasions of a large cohort study in the Netherlands. The types and severity of pupils' problems, and their school careers were studied. Around 25% of the pupils were considered by their teachers to have SEN. Results show that a substantial percentage of pupils who had been identified with SEN at the first measurement occasion were not identified with SEN three years later, whereas the same percentage had not been identified with SEN at the first occasion but was at the second occasion. Significant predictors of being identified with SEN include results from skills tests, and the teacher's views on the pupil performing below expectations, having a less favourable attitude to work, being less popular with classmates, and being more dependent on the teacher. In addition, boys are more likely to be identified with SEN in comparison to girls. Cognitive impairment and/or delayed cognitive development proved to be the most influential predictor of referral to special education. In addition, chances of a pupil being referred to special education are influenced by several other pupil characteristics. Implications of these outcomes are discussed.