BACKGROUND: The Physical Literacy in the Early Years (PLEY) intervention is a randomized mixed-methods controlled trial focused on embedding loose parts materials into the outdoor play spaces of regulated child care centres across Nova Scotia. The aim is to evaluate the efficacy of the PLEY intervention versus standard regulated childcare practice in influencing thoughts and behaviors of children, parents, and educators. METHODS: Participating early child care centres (n = 19) were randomly assigned to intervention or control sites. Intervention sites received loose parts kits at the beginning of the project while control sites received kits upon project completion. The kits included items such as rocks, tree cookies, balls, wood planks, tubes, tires, ropes, and pulleys. Children (n = 183 at baseline) had their physical activity (accelerometers) and movement skills (TGMD-3 and PGMQ) measured before and after the intervention. All centres provided responses to environmental surveys (Go NAP SACC and Site Context Questionnaire), and educators in intervention sites participated in focus group and photovoice sessions. Educators were also provided with a full day professional development opportunity (plus ongoing mentoring) focused on physical activity, physical literacy, outdoor play, risk-taking, and loose parts. Parents participated in an interview addressing active outdoor play, physical literacy, and attitudes towards risk taking during play. DISCUSSION: This study will provide a better understanding of how integrating loose parts materials into outdoor play spaces impacts children’s health, and the impact on educator and parent attitudes, beliefs, and understanding around physical literacy, active outdoor play and risk-taking during play.