Assessing individuals' social and emotional (SE) knowledge, attitudes, and skills is a complex task. It requires careful consideration of the assessment purpose, rigor, practicality, burden, and ethics. Once you have considered these factors and have determined that you are, in fact, "Ready to Assess," you are ready to act and choose an assessment tool to achieve your desired outcome. The purpose of this "Tools Index" is to help you make an informed decision on the best tool to explore these outcomes. The elements included in this document were selected to provide a brief overview of the selected outcomes tools identified by American Institutes for Research (AIR) for exploring SE knowledge, attitudes, and skills. The tables are organized according to four developmental areas: early childhood, elementary school, middle and high school, and workforce. The measures identified within each table are organized alphabetically. This document is the third component in AIR's suite of resources, "Ready to Assess." "Ready to Assess" was designed to help decision makers and practitioners make informed and ethical assessment decisions. [For "Are You Ready to Assess Social and Emotional Development? SEL Solutions Brief," see ED577553. For "Are You Ready to Assess Social and Emotional Development? SEL Solutions Decision Tree," see ED577466.]