To address the shortage of skilled workers in the 21st century, shifting demographics, competition for education funding, and the need to better serve underrepresented student populations, colleges and universities in the United States seek to increase internationalization efforts. While a number of instruments exist for measuring internationalization at the university level, few instruments are designed for measuring campus-level institutionalization, particularly at public community colleges. Moreover, current community college instruments are based on outdated literature or make use of qualitative tools that are not necessarily applicable in all settings. This study utilized an exploratory sequential mixed-method design to construct a quantitative instrument to measure institutional-level internationalization in public community college settings. Qualitative data were used to develop a theory of community college internationalization, from which the Community College Internationalization Index was developed. The CCII will be valuable for tracking public community colleges' progress in internationalization efforts.