While basic proficiency in mathematics, reading, and writing is essential, educators and parents alike would more likely list characteristics like perseverance, self-control, creativity, time management, leadership, conscientiousness, and being an effective collaborator when considering what is most important for success in school, work, and life. These characteristics are often dubbed "social-emotional learning (SEL) competencies," "noncognitive skills," "soft skills," or "21st century skills" in the literature. Although near universal at the preschool level, state adoption by states of freestanding K-12 standards targeting noncognitive skills remains a work in progress. Any effort at implementing state SEL standards must be accompanied by reliable, valid, and conceptually aligned mechanisms for determining the extent to which students and schools have met the standards. This article offers three general recommendations for consideration. First, because noncognitive skills tend to be complex and multifaceted, when feasible, multiple types of assessment should be targeted at each construct of interest; second, assessments should be standardized to ensure students and teachers are encountering comparable stimuli across school contexts; and third, that State Boards of Education and state education agencies work with experts in the field to both build noncognitive assessments and thoroughly research their measurement characteristics, validity, and fairness.