The objectives of this study were to investigate the assessment practices of in-serviceteachers and to compare the assessment practices of teachers in different subject areas, teaching levels and teaching experience. Altogether 406 in-service teachers responded to the Teacher Assessment Practice Inventory. Rasch's model was used to analyse the characteristics of the assessment practices adopted by the teachers. Differential item functioning was performed to compare the assessment practices. In-service teachers were found to often use traditional types of assessment. The assessment practices differed between language teachers and science and mathematics teachers, primary school teachers and secondary school teachers and experienced teachers with inexperienced teachers.