This study examined the variation in four assessment practices, including mandatory standardised tests, non-mandatory standardised tests, teacher-developed tests, and teachers' judgmental ratings in Kosovo and six didaktik and five curriculum countries, and associations of the four assessment practices with students' science performance, using data from PISA 2015. The main objective of the study was to place Kosovo in the didaktik-curriculum continuum, while testing the differences in the key variables between the two traditions. Relying on mean comparison, Mann-Whitney two-sample rank-sum tests, and hierarchical linear modelling for data analysis, the findings suggest that Kosovo is placed towards the curriculum end of the continuum as a result of the shift of education policy towards curriculum tradition-based policies such as standardised testing over past 20 years. Overall, the findings reveal that theoretical claims about differences between didaktik and curriculum traditions regarding teacher autonomy still hold when tested empirically and quantitatively and using assessment practices as evidence. The hierarchical linear modelling results were underwhelming, as in most sample countries the four assessment practices were not statistically and significantly associated with students' science performance, with a few exceptions. The article ends with potential avenues for further research warranted by the results of the present study.