T he goal of this chapter is to assess and discuss research and knowledge concerning the signi cance of Social and Emotional Learning (SEL) in educational practices. The chapter rst discusses the nature of learning, which is inherently social, relational and a ective. The concept and de nitions of SEL are introduced to synthesize the debate around how social and emotional experiences interact with the learning processes. Then the development of socio-emotional skills across the lifespan with regards to neurobiological, social, and cultural factors is discussed, highlighting the important role of assessment in bringing a disciplined focus to SEL in schools. Applied research that describes interventions, programmes and policies geared towards promoting SEL and that can inform educational practices is then presented. The chapter concludes by recommending that SEL practices and policies should be responsive to context and culture, be informed by neurobiological development, and take into account educators' social and emotional capacities.