Civic engagement is crucial for individual well-being, positive social change, and the health of American democracy. Little is known about how individuals come to be engaged citizens, yet we theorize that the roots of civic engagement begin in childhood and that the development of civic engagement is intertwined with growth in character and competencies and supported by contextual assets. Through this project, we plan to empirically investigate a unifying theory of civic development across childhood and adolescence. We propose that character, competencies, and contextual assets directly and positively relate to youth civic engagement, and further posit that these personal and environmental characteristics interact dynamically to foster engaged citizenship. Our theory and research aims are innovative; besides this proposal, little research examines civic development across childhood and adolescence, incorporates an interdisciplinary developmental approach, or fully considers the role of contexts. Results should advance developmental theory, illuminate the role of character strengths, establish valid and reliable measures of youth character and civic engagement, and identify the contexts that support positive youth development. To achieve these goals, our rigorous design utilizes a socioeconomically, ethnically, and geographically diverse sample; youth and parent data; and a mixed methodology. Findings will be widely disseminated via peer-reviewed articles, applied reports, symposia, a website, and a webinar. A toolkit of measures and empirical tests of theory will stimulate new research across disciplines. Actionable steps for parents, schools, and communities will enhance everyday practices of character and civic education. The enduring impact will consist of encouraging character strengths and engaged citizenship in young people, which has implications for the well-being of the youth and for democracy.