The purpose of this study was to determine the preschool teacher's professional development (PD) needs about education for sustainability (EfS) as the first stage of a PD project. The general knowledge of teachers on sustainable development (SD) and their experience in preparing and implementing EfS activities was investigated. The data were collected from 1126 participants via a survey to determine preschool teachers' knowledge level about SD and their practice to develop a PD program. Most preschool teachers acknowledge the term SD and revealed limited SD knowledge. Organizing learning centers and using outdoor learning environments on EfS were seen as challenging tasks for them. Few of them find themselves competent in family participation efforts for SD.