High-quality outdoor environments (OEs) are essential for young children's physical, emotional, and intellectual development. The goal of this study was to explore the attributes of high- and low-quality OEs in early childhood education and care (ECEC) settings identified by different stakeholder groups. We conducted 41 focus groups/interviews comprising ECEC practitioners; policy and oversight professionals; parents; children; and equity, diversity, and inclusion specialists. Using thematic analysis and descriptive statistics, the following nine key attribute categories of high- and low-quality OEs were identified: physical space, natural elements, equipment and materials, program intent, activities, interactions, safety and maintenance, professional development, and barriers to implementation. Descriptive differences across the groups were found; notably, four stakeholder groups prioritized the environment's setup, while equity, diversity, and inclusion specialists gave equal emphasis to natural elements and programming. These findings provide clear definitions of quality for OEs in ECEC settings. This information can help guide research and policy on how to incorporate high-quality outdoor spaces into ECEC programs, recognizing the significance of OEs for children's development.