This article presents findings of an empirical analysis which show that the level of candidate countries' compliance with the accession conditionality is positively associated with the extent of annual pre-accession monitoring. Focusing on conditionality and labour rights in 11 post-communist CEE candidate countries, in the period between 1998 and 2009, the study analyzes the relationship between the extent of annual monitoring and the post-communist CEE candidate countries' labour rights scores, two years later. A positive, statistically significant association between the two variables is found. The article proposes an explanation of the findings based on discursive institutionalism, and integrates this with the theory of conditionality. According to discursive institutionalism, monitoring supported conditionality through strategic, normative and communicative mechanisms. It strengthened certainty regarding rewards and sanctions, reduced domestic costs of compliance and supported normative convergence.