Education in the 21st century is awakening to a call for students who are not only proficient with academic content but who also have developed the social and emotional (SE) knowledge, attitudes, and skills that are necessary for success in college and careers. This brief refers to that combination of knowledge, attitudes, and skills as SE competencies. SE competencies enable students to harness their academic knowledge and turn that knowledge into action. Research suggests that the development of academic knowledge and SE competencies is inextricably linked and the two elements mutually reinforce one another (Farrington et al. 2012). Leaders in education have recognized the critical need to support students developing SE competencies and, increasingly, have turned their attention to assessments to ensure accountability to standards that emphasize them (Dusenbury, Zadrazil, Mart, & Weissberg 2014). Although this shift in focus toward a more holistic approach to student success may be a significant and positive advance for education, it begs certain questions about policy and practice. This brief and the accompanying "Ready to Assess Decision Tree" and "Tools Index" aim to provide policymakers and leaders in education with (1) an overview of the developing assessment landscape and (2) a framework and guidance for deciding if and when they are ready to assess SE competencies. [For "Are You Ready to Assess Social and Emotional Development? SEL Solutions Decision Tree," see ED577466. For "Are You Ready to Assess Social and Emotional Development? SEL Solutions Tools Index," see ED577551.]