This study was conducted to introduce the concepts of social and emotional learning(SEL) that was found effective in enhancing social-emotional competencies, preventing problem behaviors, and improving academic performance and to examine the necessity and sustainability of schoolwide SEL in Korean school systems pursuing academic excellence. Theoretical literature, empirical studies, SEL curricula, the U.S. laws stipulating SEL learning standards, Singapore’s SEL practices, and SEL lesson plans developed by Korean teachers were reviewed. As a result, the construct of social-emotional competencies was found to consist of five components(i.e., self-awareness, social awareness, self-management, relationship skills, responsible decision-making), and SEL was defined as the strategic process of implementing many school-based prevention and intervention services designed to enhance social-emotional competencies in a coordinated and integrated manner. Such process consisting of three phases(i.e., readiness, planning, implementation) and 10 stages included six sustainability factors. Methods of implementing SEL in schools were categorized into either a person-centered approach(e.g., skills training) or an environment-centered approach(e.g., creating caring, supportive and safe climate). It was inferred that the method of infusing SEL into academic learning would be more acceptable to Korean school systems than that of implementing SEL curricula in the group counseling manner. Prior empirical research showed that schoolwide SEL would improve students’ school-related attitude, behavior, and academic performance as well as teachers’ self-efficacy and teaching practices. For such positive outcomes, it would be necessary to identify roadblocks to implementing schoolwide SEL in advance and to prepare plans to break through them. Finally, the significance and challenges for adopting and implementing SEL in Korean school systems were discussed and suggestions for further research were made.