The relationship between prosocial behavior (PB) and cognitive abilities has been well documented. This study explored genetic and environmental overlaps in the relationship between PB and verbal and non-verbal abilities. Participants included 3179 twins attending public secondary schools in Lagos State in Nigeria (mean age = 14.6 years, SD = 1.7 years). The PB scale of the Strengths and Difficulties Questionnaire was used to measure PB. The set B of the Mill-Hill Vocabulary test (MHV) and Raven's Standard Progressive Matrices Plus (SPM) were used to measure verbal and non-verbal ability, respectively. The MHV-PB and the SPM-PB correlations were 0.29 (95%CI = 0.26, 0.32) and 0.19 (95%CI = 0.15, 0.23), respectively, indicating that PB is more strongly related to verbal than to non-verbal ability at the phenotypic level. Bivariate model-fitting analyses revealed that additive genetic correlations were 0.73 (95%CI = 0.59, 0.92) for MHV-PB and 0.55 (95%CI = 0.40, 0.82) for SPM-PB, respectively. Neither shared nor non-shared environmental correlations were significant. Bivariate heritability was estimated at 1.0 (95%CI = 0.65, 1.00 for MHV- PB and 95%CI = 0.60, 1.00 for SPM-PB), indicating that the relationships between PB and two cognitive measures were mediated entirely by common genes. Multivariate Cholesky model-fitting analysis showed that while MHV explained 10% of additional additive genetic variance of PB above and beyond the common genetic variance, SPM became non-significant after the common genetic variance was controlled. These results suggested that the relationship between cognitive abilities and PB may be largely driven by verbal ability.