The implementation of Education for Sustainable Development (ESD) in formal education is an arduous process. A much reported issue is that teachers do not perceive ESD as part of their task. As ESD should be implemented through whole-school approach this is identified as one of the major barriers to successfully bringing ESD into formal education. The current study uses the most recent Swedish TIMSS data Sweden for grade 4 classroom teachers, and for grade 8 biology and science teachers to answer three questions: (1) How well prepared do teachers feel to teach ESD? (2) According to teachers, is ESD supported in/by the whole school? (3) How often do teachers participate in ESD professional development? Using data from over 1000 Swedish respondents, the study shows that elementary and science teachers feel ill prepared for ESD. Biology teachers in grade 8 feel most prepared, but their mean score is also below the value 2 (indicating that they do not even feel ‘somewhat’ prepared). Our study also reveals that students are not very involved in the implementation of ESD. This is problematic since ESD focusses on their participation. While PD rates are low for all teachers in the sample we see that when grade 4 and grade 8 science teachers do participate in such programs they feel better prepared to bring ESD into their classroom. At the same time we have to underscore that across PD topics in TIMSS, ESD is at the lowest level (around 13%, with other topics averaging 25 to 45%). Yet, these results show that PD is key to the successful implementation of ESD.