Students' academic performance in Social Studies has been poor for the past years. Blame has been levelled on teacher factors, students' attitude towards the subject, and lack of learning materials. This study therefore seeks to find out if socio-cultural diversity among students is responsible for their poor performance in Social Studies. The purpose of this study is to examine learners' socio-cultural diversity as determinant of academic performance in Social Studies in Calabar Education Zone of Cross River State, Nigeria. To achieve the purpose of this study, two hypotheses were formulated as a guide. Literature was reviewed based on the two identified variables of social and cultural diversity. Both theoretical and empirical review was carried out. Survey research design was adopted and a sample of 488 students was selected through simple random technique from a population of 5,039. Questionnaire was used for data collection. The instrument was face validated and the reliability estimate was established through the Cronbach Alpha method with coefficient of 0.75 and 0.72. Kuder Richardson formula -20 was used for social studies achievement test with a reliability coeffient of 0.81. Pearson Product Moment Correlation and Independent t-test were employed to test the hypotheses at 0.05 level of significance. The result revealed that, social and cultural diversity significantly influence Social Studies students' academic performance in Calabar Education Zone. It was recommended that, sociocultural diversity of learners should be considered while teaching so that every learner will benefit from the instruction.