Education plays a central role in preparing young people to engage thoughtfully in civic and community issues and to wrestle with complex dilemmas in the public domain. As a democracy, our system of governance offers multiple pathways through which people living in the country can influence how civic issues and dilemmas are addressed. Historically, such preparation has been viewed as the purview of K-12 civics courses and U.S. history courses. However, Educating for Civic Reasoning and Discourse (Lee et al., 2021b) from the National Academy of Education articulates a broader view. It argues that the multiple dimensions of civic reasoning and discourse require explicit attention across all the subject matter areas taught in U.S. schools and at every level of K-12 education (see Box A for definition of civic reasoning and discourse). To illustrate civic learning across subject-specific content areas, we present a collection of practitioner reports addressing teaching practices in five areas of learning: 1) mathematics; 2) science; 3) literacy; 4) history and social studies; and 5) digital citizenship education. Undergirding these reports is the assumption that engaging students in the development of civic-related knowledge, skills, dispositions, and ethics across academic disciplines is important for students' civic preparation. Designed for teachers, school and district leaders, and disciplinary practitioner organizations, these reports offer guidance and exemplars of instruction to illustrate how teachers can design lessons that meet both the demands of disciplinary learning and the needs of civic engagement. These approaches take to heart the necessity for learning activities to contribute to youths' development of democratic values, intellectual capacities, and the ability to navigate differences in perspectives in search of a common good. The reports also take into account the different stages of cognitive, biological, and social-emotional development of young people and offer examples of lessons across grade levels. This introduction provides an overarching framing for the series of five practitioner reports. It provides a description of essential components of civic reasoning and discourse; next, it reviews relevant research on learning and development, brain development, and classroom climate that facilitates students' development of civic capabilities. Finally, this introduction provides recommendations to strengthen civic learning across K-12 classrooms.