This paper aims at answering the following two questions; one is "How can social studies move from contents-focused to contents-skill-balanced?" and the other is "How can social studies' unique skills and competency that extend beyond the boundary of individual subject be cultivated simultaneously?" To answer these questions, authors analyzed "The College, Career, and Civic Life (C3) Framework" and its four example units, which are designed by NCSS to promote inquiry-based curriculum and cultivating competency within social studies. The four example units were based on the "Inquiry Arc," which is the core of the framework: (a) developing questions and planning inquiries, (b) applying disciplinary tools and concepts, (c) evaluating sources and using evidence, and (d) communicating conclusions and taking informed action. After the analysis, authors could discover the framework's three characteristics. (1) C3 Framework integrates social science disciplines into social studies by using them as lenses to understand society. (2) The framework also achieves a good balance between doing social studies and developing competencies that goes beyond a subject through adapting Inquiry Arc. (3) The framework gives discretionary power to curriculum designers including teachers, so they should be in charge of their curriculum as gatekeepers.