Indigenous mourning rituals face ongoing threats from globalizing forces, and despite ongoing cultural evolutionary research on the prosocial effects of religion, limited attention has been paid to how mourning rituals foster individual and community wellbeing and resilience. In light of these issues, our project investigated how rituals are practiced and transmitted among the Luhya community of western Kenya, and how these mourning rituals can help enhance individual and community wellbeing and cooperation. We specifically aimed to answer three interrelated questions: (1) What is the therapeutic value of Indigenous mourning rituals? (2) Do mourning rituals promote cooperation? and (3) How does participation in mourning rituals contribute to cultural transmission? These questions were answered using qualitative and quantitative methods including focus groups, quantitative interviews, behavioral observations, and psychometric tests. We did focus group discussions with 45 community elders, 30 bereaved adults and 30 bereaved adolescents; interviewed 8 religious leaders; did 20 observations and 40 adolescent free listing and 280 psychometric assessments with bereaved members of the community. Our research findings identified about 25 mourning rituals which were tested against community cooperation using the prosociality scale. The study established a weak positive correlation between rituals participation and prosociality which implies that rituals enhance community cooperation.