This chapter investigates the variations in students’ reading achievement in IEA’s Progress in International Reading Literacy Study (PIRLS) 2021 across different education systems in the Dinaric region. In particular, it focuses on how these results are distributed between the gender and socioeconomic status (SES) of students. Additionally, the study explores the extent to which affective and contextual well-being factors contribute to differences in reading achievement. In the PIRLS 2021 study, the Dinaric education systems exhibited varying levels of reading achievement, ranging from 420 points in Kosovo to 557 in Croatia. Four out of the seven education systems observed a rather large percentage of low-achieving students (below 400 points), and a significant gender gap in reading achievement was observed, with girls outperforming boys. The results also show students’ SES, reading self-confidence, and physical well-being significantly affect their reading achievement in all the education systems that participated from the Dinaric region. Additionally, in all education systems, student bullying and students engaged in reading are also significantly related to reading achievement with the exception of Albania. The student well-being factors together accounted for a large part of the variation in students’ reading achievement in different education systems. Furthermore, a substantial proportion of the variation in reading achievement between schools can be attributed to the differences in socioeconomic composition of the schools. The findings in this chapter can contribute to the design of effective education policies and programs in the Dinaric education systems, supporting both students and teachers in achieving the desired outcomes in reading literacy.