This Open Access book provides an overview of research being undertaken in Europe about young children's (1-8 years old) mathematics education. Exploring a wide variety of different environments wherein mathematics concepts in childhood education, this book encompasses the most important findings of the POEM6 conference. Following feedback at the conference, participants have the opportunity to expand the papers into full length book chapters, which will then be peer-reviewed. This book is especially suited for educators and researchers interested in the development of mathematical conceptualizations in early childhood educational environments.