With the progress of the DESD, increasing numbers of researchers have been developing indicators to effectively measure the implementation of ESD in formal, informal and non-formal education. This paper aims to measure the implementation of ESD in secondary school curricula in three countries carrying the fingerprints of a developed (Germany), post-colonial (Mexico) and post-socialist (Romania) condition. The authors tested a set of four indicators measuring the depth and breadth of implementation. The results show that ESD continues to exist as (hyper-) specialized add-on knowledge in an overcrowded curriculum (Jucker, 2011) that seems to further differentiate between high- and low-status knowledge (Williams, 2008). The tested indicators offer an insight into the depth and breadth of ESD implementation across the entire curriculum.