Many education systems worldwide have dedicated a significant amount of resources to improve quality levels in early childhood education and care. Research can contribute to this goal by providing information about conditions of high-quality education and care and reasons for changes in the quality provided to children. This study therefore analyzes the stability of educational quality and patterns of dependency of process quality on possibly determining context factors over a period of 3 consecutive school years to detect mechanisms of change and patterns of quality. Longitudinal data of a field study with annual assessments in 97 German classrooms were analyzed via growth curve analyses using Bayesian estimation. The analyses revealed an increase in process quality provided in the classrooms. Classroom composition characteristics showed strongest relations to status and change of process quality; allocated resources and characteristics of the professional staff were less strongly related. (author abstract)