This chapter discusses three main topics: (1) volunteer as a form of civic engagement, (2) Science, Technology, Engineering and Mathematics (STEM), and (3) basic skills including literacy, numeracy and digital problem-solving skills. Volunteering, STEM background, and basic skills are important social and economic indicators of societies. Yet, little is known about volunteer participation by STEM background and basic skill proficiencies in the U.S. population. An analysis of the Program for International Assessment of Adult Competencies, U.S. restricted use file data showed that adults with a STEM background are more likely to volunteer than those without. Also, when adults with a STEM background have greater basic skill proficiencies, the likelihood of volunteering is even higher. That is, the positive associations between volunteering and a STEM background is likely be moderated by basic skill proficiencies. Based on the findings from this study, preliminary policy implications and important future research areas are evaluated. [This report was published in: "Handbook of Civic Engagement and Education," edited by S. Wiksten and R. Desjardins, Edward Elgar Publishing, 2022.]