Internationally, differentiated instruction (DI) is suggested as a teaching approach that can help teachers to meet the varying learning needs of students in the classroom. However, not all teachers reach a high level of implementation. Personal characteristics of the teacher as well as teaching quality may affect the degree and quality of DI. In addition, several classroom-, school-, and country characteristics may affect DI practices. In this chapter, literature is reviewed about personal factors, teaching characteristics and contextual factors influencing DI. Findings from the literature are connected to analyses of classroom observation-data collected in six countries including Indonesia, the Netherlands, Mongolia, Pakistan, South Korea and Spain. The chapter aims to contribute to insights into factors related to DI and into differences in these associations between the six countries. This chapter concludes by discussing scientific and practical implications. © The Author(s) 2023. All rights reserved.