Education systems around the world are increasingly recognising that social and emotional skills (SES) are essential for students and societies. This paper contributes to the Innovative approaches to measuring social and emotional skills project, which aims to complement self-report measures of SES with more direct assessments. It addresses criticisms of the OECD framework for SES used by the OECD Survey on Social and Emotional Skills and discusses the use of the Big Five model as an underlying structure for organising SES. The paper then examines the teachability of SES through a comprehensive literature review. In addition, it reviews the evidence for the relationship between different SES and key life outcomes. The paper also seeks to reconcile divergent conceptual understandings in the literature by providing a clear definition of SES and highlighting discrepancies in skill definitions. The conclusions of the paper identify gaps in current research, highlight teachable skills with notable predictive value SES relevant for educators and policy makers, and support the development of direct SES assessments.