The US Peace Corps has been operating programs globally since 1961 with an enduring mission toward international friendship and world peace structured around clear goals that emphasize cross-cultural learning objectives. Little is known about whether the program has a positive effect on US soft power abroad and, if so, the magnitude of that influence. This paper examines the impact of Peace Corps programming in foreign states on US public diplomacy objectives. The primary research aims to understand the relationship between indicators of a foreign population’s favorability toward the US and Peace Corps participation to determine the effects of program size as well as program presence and removal. Pew Research Center US favorability scores were analyzed alongside Peace Corps volunteer cohort sizes between years 2004 and 2016 among 20 sample countries. The findings indicate a positive and statistically significant relationship between the size of the Peace Corps volunteer cohort and US favorability. Each additional volunteer increases favorability toward the US by 0.12 points. The results are robust to the inclusion of additional soft power factors. Supplementary findings illustrate that the removal of Peace Corps programming may adversely impact favorability toward the US, establishing the negative soft power effect of ceasing participation.