Play has the potential to transform the global learning crisis. In infancy and early childhood, play builds a strong foundation for later learning by improving brain development and growth (Goldstein, 2012). In education systems that lack capacity to support children effectively, play brings its own powerful engine to drive learning—the joyful, engaged intrinsic motivation of children themselves (Zosh et al., 2017). In this way, play contributes to the holistic development of children, helping to prepare them for the challenges of the current and future world. Accordingly, there is an urgent need to improve measurement of playful learning, to be able to add to the evidence base on what the benefits of play are, how playful learning takes place, and how it can be promoted at home and at school across the lifespan. This presentation focuses on a renewed conceptualization of playful learning and describes an innovative approach to measuring how settings contribute to playful learning for children ages 0 to 12, supported by the Lego Foundation. The settings we examine include homes, classrooms and ECD centers. Following Tseng and Seideman (2007), we view settings as consisting of social interactions (i.e. between teachers or caregivers and children) and the organization of resources (e.g. learning materials, games). First, we will present our conceptual framework which identifies six constructs to guide our measurement strategy. The constructs, such as ‘support for exploration’, represent the ways in which a setting supports playful learning. Next, we will present our contextualization framework which guides how we are adapting and modifying the measurement tools to different contexts. The tool consists of a protocol to observe adult-child interactions and survey measures conducted with teachers, caregivers and primary school pupils. As part of the development process for these measurement tools, observation and survey measures will go through a three-phase development process in Kenya, Ghana, Colombia, and Jordan. The Build phase involved collecting qualitative data from teachers, caregivers and students to understand their perception of playful learning and how it is supported at home and at school. Next, an Adapt phase took place where the initial versions of the measurement tools underwent cognitive interviewing, field adaptation, and a small pilot to adjust and extend the items in the tool. The third Test phase is a full pilot of the instruments, and the data will undergo rigorous psychometric analyses to review the validity and reliability of the tools in the four country contexts. We will use the results to adjust the instruments and to finalize the conceptual framework and contextualization strategies. The final toolkit will be publicly available towards the end of 2022 with supporting materials for contextualization, piloting, training and analysis. The toolkit will be available on a public platform designed to promote sharing of data collected using the tool and to collaborate to continually improve approaches to measuring support for playful learning.