This literature review provides an up-to-date comprehensive overview of what is known about process quality in early childhood education and care (ECEC) provision for children under age 3. It builds on empirical studies published in peer-reviewed journals between 2010 and 2019. Current views on process quality for children under age 3 highlight that process quality is a multidimensional and value-laden concept. But there is growing agreement on several core features, namely, the prominence of warm/responsive interactions, the value of both education and care and the importance of strong partnerships with parents. Recent studies show positive links between process quality and infant/toddler development. The evidence is relatively robust in terms of the influences of staff pre-service training, group size and ratios for process quality in centre-based settings, although more limited for home-based settings. Nevertheless, consideration of complex interactions among structural features is noted. Recent studies further advance knowledge on more fine-grained understandings of process quality. (author abstract)