At Lego Foundation, we have been writing a white paper about Play facilitation: the science behind the art of engaging young children. The writers are Hanne Jensen, Angela Pyle, Jennifer M. Zosh, Hasina B. Ebrahim, Alejandra Zaragoza Scherman, Jyrki Reunamo and Bridget K. Hamre. Play is important in developing skills, learning, solving problems, in relationships, health and societal development. However, not all play is beneficial. Play facilitates learning when it is joyful, meaningful, actively engaging, iterative and socially interactive. In the paper, it is considered important that play is integrated to all activity, including instruction. The paper includes a lot of research results based on our project. Thank you for everyone for their contribution. The paper is disseminated world-wide by Lego and it is launched officially 27 February 2019 in South Africa.