This study proposes the foundations and principles of the emergent curriculum in preschool. For this purpose, we address the conceptual and documentation analysis of this curriculum. Hence, using the research method of “, regressive inference”, , the foundations of the emergent curriculum have been deduced. Firstly, all instances of emergent curriculum were extracted from 60 valid national and international documents (including books, articles, written and electronic thesis) from 1994 to 2020. Then, the collected data were classified in three stages,including open coding, axial and selective data in order to analyze them. Approximately, 31 selective codes were recognized. In addition, the principles were inferred by use of the “, progressive inference”,method. Since, this research investigates the effective documents in order to understand the research problem, its employed sampling is considered purposeful. To validate the results, the coding steps were carefully reviewed about 10 times in interaction with curriculum planning and philosophy of education experts. The most important findings about nature are that emergent curriculum is a flexible, dynamic and multidimensional spiral phenomenon with different cross-sections. The main foundations are that child is a flexible creature with comprehensive dimensions, social identity, and unique talents. Knowledge is exploratory, dynamic and innovative and corresponding to children’, s interests. Some of its basic principles include a holistic view of the child and attention to individual differences, providing the possibility of exploration, Relation to the phenomenon under study, hypothesizing.