Social and emotional learning (SEL) is the process through which children and adults acquire and effectively apply the knowledge, attitudes, and skills necessary to understand and manage emotions, set and achieve positive goals, feel and show empathy for others, establish and maintain positive relationships, and make responsible decisions. 

SEL programming is based on the understanding that the best learning emerges in the context of supportive relationships that make learning challenging, engaging, and meaningful. 

Social and emotional skills are critical to being a good student, citizen, and worker. Many risky behaviors (e.g., drug use, violence, bullying, and dropping out) can be prevented or reduced when multiyear, integrated efforts are used to develop students' social and emotional skills. This is best done through effective classroom instruction, student engagement in positive activities in and out of the classroom, and broad parent and community involvement in program planning, implementation, and evaluation. 

From:  http://www.casel.org/social-and-emotional-learning/