Background: Traditionally, special educational needs (SEN) were often defined in terms of child deficits. Recently, there has been a tendency to define SEN in terms of (additional) support needed in the classroom. However, little is known about how teachers define students with special educational needs. To close this gap, characteristics of teacher-identified students with special educational needs in Dutch mainstream primary education were explored. In order to identify these students, 52 teachers from 14 mainstream primary schools were asked: Which of your students are in need of additional support to achieve set educational goals? It was made clear that educational goals could pertain to a specific subject, but also to a student's social, emotional or behavioural development. Purpose: The study aims at exploring characteristics of students with special educational needs in mainstream primary education of those identified by teachers as in need of (additional) support to attain set educational goals. When teachers assess their students' special educational needs, it is likely that they take students' characteristics into account that could be hindering the learning processes: students' perceived self-competence, teacher-perceived students' on-task behaviour, teacher-perceived relationship with the students and teacher-perceived students' internalising and externalising (problem) behaviour. Thus, the present study was designed to compare these characteristics of teacher-identified students with norm-referenced groups. Sample: A total of 151 students (58.9% boys; mean age 9.7 (0.98)), range 8-12 years) were identified by their teachers as in need of additional support to accomplish set educational goals. Methods: Validated questionnaires measured students' perceived self-competence, teacher-perceived students' on-task behaviour, teacher-perceived relationship with the students and teacher-perceived students' internalising and externalising (problem) behaviour. Scale scores of teacher-identified students were compared with norm-referenced groups. Within-group analysis compared high- to low-achieving teacher-identified students. Results: About two-thirds of teacher-identified students with special educational needs were male and about 40% were scoring higher than the national average in key skills. The majority had no clinical diagnosis (boys 76.4%, girls 82.3%). On average, the characteristics of teacher-identified students with special educational needs did not differ radically from the norm-referenced groups. However, teacher-identified students showed significantly more problematic scores on the scales "depression" and "self-competence" than the norm-referenced group. Within-group analysis showed several significant differences between high- and low-achieving teacher-identified students with special educational needs. Conclusion: The group of teacher-identified students with special educational needs was heterogeneous, including boys and girls, high- and low achievers, and mainly children without a clinical diagnosis. The teachers' view demonstrated in this study underlined the multifaceted nature of special educational needs. Therefore, these students should not be regarded a homogenous group that can be defined categorically, rather a group characterised by a spectrum of needs with many variations. Further research is being done by the authors to discriminate sets of support needs of teacher-identified students with special educational needs.