Abstract
Based on the self-determination theory (SDT), this study used a mixed-methods (i.e., quantitative and qualitative approaches) design to explore the role of basic psychological need satisfaction (BPNS) played in sustained volunteering. Quantitative analysis of 803 college student volunteers revealed that competence and relatedness need satisfaction had significant associations with sustained volunteering, while autonomy need satisfaction did not. Furthermore, latent profile analyses identified five profiles of BPNS: low (Profile 1), relatively low (Profile 2), moderate (Profile 3), low autonomy-high competence and relatedness (Profile 4), and high (Profile 5). Volunteers in Profile 4 and Profile 5 reported higher sustained volunteering than those in other profiles. Subsequent qualitative synthesis of interview data from 33 college student volunteers found that competence need satisfaction (45.58%) was mentioned most frequently among the factors promoting sustained volunteering, then followed by relatedness (27.43%) and autonomy need satisfaction (11.06%). These findings highlight the important role of BPNS, especially competence and relatedness need satisfaction, in promoting college students' long-term volunteering.