Social-emotional learning (SEL) programs and practices have garnered increased interest over recent years, primarily in response to a preponderance of research regarding universal, targeted, and intensive SEL programs. Along with this interest have come repeated calls for the adoption of standards for SEL at the state level. A systematic review was conducted to examine existing preschool and kindergarten through 12th grade SEL standards across all 50 states within the United States and the District of Columbia. This review included an examination of freestanding SEL standards, as well as those embedded within health, physical education, and/or counseling standards. Coded variables of interest included the specification of age- or grade-related categories (e.g., birth to age 3, grades K-2) and standards alignment with the five Collaborative for Academic, Social, and Emotional Learning (CASEL) core competencies (i.e., self-awareness, self-management, social awareness, relationship skills, and responsible decision making). Results demonstrated every state has freestanding preschool SEL standards; however, only 11 states have freestanding SEL standards at the K-12 level. SEL standards were much more prevalent within health education standards across K-12 settings. Implications for practice and research are discussed in relation to the development and appropriateness of age- and grade-level SEL standards.