Early childhood education and care programmes provide opportunities to enhance children's learning and development, especially when high-quality learning experiences and educator-child interactions are embedded within them. However, the quality of early childhood education programmes varies greatly. Quality in early childhood education and care is conceptualised in three domains: structural, process and system. Understanding how to drive quality improvements in early childhood education and care relies on clear, consistent evidence concerning each of these domains, however, the current literature is not comprehensive. This scoping review maps the extent and consistency of the research literature in each domain of quality to identify knowledge gaps and inform future research. Through a search of the peer-reviewed literature, 85 meta-analyses and systematic reviews meeting our inclusion criteria were identified. We found a wide variation in the number of included studies in each domain and sub-domain of quality. We found the greatest number of meta-analyses and systematic reviews related to "programmes, interventions, and curricula" (process quality) and "professional development and support" (structural quality). The literature included in this scoping review is heterogeneous and of varying methodological quality, with inconsistent or contradictory findings. The research is most consistent in relation to "pedagogy, professional development and support, and programmes, interventions, and curricula" (process quality) and "learning environments" (structural quality). Interactions between the different domains of quality are complex and future research should focus on the associations between different features of quality in early childhood education programmes and practices that are critical to implementing successful continuous improvement initiatives.