A Research report submitted to Mzumbe University – Mbeya Campus College in partial fulfillment of the requirement for the award of Bachelor of Human Resource Management (BHRM) of Mzumbe University.The purpose of this study was to examine the effects of workforce diversity on employee performance of an organization in Mbeya region. The specific objectives were; to find out the effects of employee age differences on organizational performance, to examine the influence of employee education level on organizational performance and to assess on the impact of employee years of working on organizational performance The study employed case study research design method. To facilitate gathering of relevant data questionnaire and interview questions were used. The study centered on National Health Insurance Fund to examine the level of diversity practiced in terms of age, educational and work experience in Tanzania organizations. Data was collected and analyzed using the excel, format percentages and frequencies tables were used for the descriptive aspects. The research findings showed all aspects of workforce diversity used in the study have a significant relationship with employee performance. It was also discovered that age, educational and work experience diversity have strong influence on employee performance. It is recommended that the management should proceed in upholding its diversity policies and practices in order to increase the benefits of diversity. The management should ensure that all employees are properly trained on diversity issues as these trainings will enable employees to change unconscious behaviors that hinder diversity and inclusion practices. Generally, this study will add value to existing literature on diversity and it will aid the NHIF staff and the society as a whole to fully understand diversity issues, how to manage it and how to reap the benefits.