The results of the Effective Provision of Pre-school Education (EPPE) study from England (United Kingdom) have also shown that key explanatory factors for high-quality ECEC were related to “staff with higher qualifications, staff with leadership skills and long-serving staff, trained staff working alongside and supporting less qualified staff, staff with a good understanding of child development and learning” (Siraj-Blatchford, 2010). Higher proportions of staff with low-level qualifications were related with less favourable child outcomes in the socio-emotional domain (social relationships with their peers and cooperation). There is no simple relationship between the level of education of staff and classroom quality or learning outcomes.