This study examines the impact of acculturation on Korean Americans’ decisions to volunteer either for secular and religious organizations or informally. The results show that language difficulty and Korean identity lower the likelihood of secular volunteering, but not of informal volunteering. Koreans who are Protestants or Catholics, and those with higher levels of education, are more likely to volunteer formally, but not informally. The findings indicate formal volunteering is strongly associated with acculturation factors, along with personal and social variables but informal volunteering appears to be independent from and not complementary of the other two types of volunteering.