Theory and practice of Education for Sustainable Development (ESD) in early childhood education (ECE) is still an emerging issue in all over the world. ESD practices should be integrated into existing ECE programs considering the role of eco-school program and preschool teachers at all levels of education both in nationwide and worldwide. Eco-schools program is one of the best practices representing ESD in formal education system. In addition, early childhood teachers either working at eco-preschools or not, is the main vehicle in inclusion of ESD teaching practices into existing curriculum. In the current study, early childhood educators' knowledge about Sustainable Development (SD), attitudes towards SD, childhood location and household type, Non-Governmental Organization (NGO) membership, and previous experiences on implementing ESD related activities were investigated as the possible predictors of ESD teaching practices in eco and non-eco preschools. The results of the Hierarchical Linear Modeling (HLM) analyses revealed that NGO membership of preschool teachers along with their attitudes are the predictors of ESD teaching practices in eco preschools. On the other hand, previous experiences on implementing ESD related activities and attitudes towards SD are associated with teachers' ESD practices in non-eco preschools. In conclusion, the current study captures the existing situation of ESD integration into ECE curriculum on the behalf of preschool teachers. It may be reminded that teachers are the most important human resource for promoting ESD.