The Every Student Succeeds Act (ESSA) requires state accountability systems to include indicators of "school quality and student success" along with indicators of academic outcomes. The new law provides an important opportunity for states to broaden the definition of student success to include measures of students' social-emotional, as well as academic, development. Schools can support students' social-emotional development by fostering a supportive school climate, as well as through explicit instruction. When classrooms are safe and engaging, and learning is both supported and rewarding, students feel connected and efficacious--which allows them to develop the social and emotional, as well as academic, skills, habits, and mindsets needed to succeed in life. This paper provides a framework for considering how measures of social and emotional learning (SEL) and school climate may be incorporated in an accountability and continuous improvement system. We conceptualize such a system as multitiered, and designed to provide useful information about school status and progress at the state, district, and school levels. This report offers guidance on how states and districts might determine which measures of social and emotional learning, development, and supports they can use in different parts of their accountability and continuous improvement systems, and how they might use the resulting data. The authors consider (a) measures of students' social and emotional skills, habits, and mindsets; (b) measures of school climate and supports for SEL; and (c) measures of student outcomes, such as chronic absenteeism and suspension rates, that are related to school climate and supports for SEL. [For "Encouraging Social and Emotional Learning: Next Steps for States. Policy Brief," see ED606439. For the brief, see ED606775.]