The broad objective was to investigate the Effect of Diversity in Corporate Social Responsibility on Organisational Performance: A Study of Nigerian Breweries Plc., Abia State, Nigeria. The specific objective sought to determine the effect of legal social responsibility on productivity of Nigerian Breweries Plc., Abia State, Nigeria and examine the effect of Ethnical social responsibility on effectiveness of Nigerian Breweries Plc., Abia State, Nigeria. The study adopted survey research design. This study employed both primary and secondary sources of data. The target population of this research consists of the entire workforce of the Nigerian Breweries Plc., Abia State. Taro Yamane’s formula was used to determine the sample size of the study which is 184. A total of one hundred and eighty-four (184) copies of questionnaire was administered to employees of Nigerian Brewery to examine how diversity in corporate social responsibility on organizational performance. However, from the 184 administered copies, 175 copies were properly filled and retrieved by the researcher and his assistants, implying that nine (9) copies of the questionnaire lost in the process. Hence, 175 respondents became the valid sample size of the study, since it is unethical and highly prohibited for researchers to manipulate data for a particular study in order to avoid uncertainty, unreliable and porous results. Thus, 95.1% (175) copies of the administered questionnaire was retrieved and confirmed. The sample technique was a simple random technique. The instrument designed for this study was subject to screening by experts. The rationale is to ensure that there was study topic, objective, research questions and hypotheses. Simple regression model was used to test the hypotheses of the study. The findings of the study stated that legal has a significant effect on productivity of Nigerian Breweries Plc. and Ethics CSR has a significant effect on effectiveness of Nigerian Breweries Plc. In conclusion, social corporate responsibility creates ethical work climate which reflects the collective moral reasoning of organization and members of the public. The study recommended that corporate organization like Nigerian Brewery needs to form a committee that scan the society in order to identify the pressing economic needs of the society.