A Dissertation submitted to Mzumbe University, Dar es Salaam Campus College in partial fulfilment of the Requirement for the award of Master’s Degree of Business (MBA) of Mzumbe University.The aim of this study was to assess the impact of employee training and development on improving organization performance, Tanzania Commission for AIDS being a case study. Specifically, the study focused on getting the perception of employees in terms of training and development programs at TACAIDS, effects of employee training on performance of the organization, and the challenges facing TACAIDS in providing training to its employees. Purposive sampling was used to obtain 35 respondents. Questionnaires and interviews were used as instruments of data collection. The study findings show that there is relatively high level of awareness of the training activities provided by the organization as noted by 81% of the respondents. The training and development has improved organization performance throuugh new ideas and skills that have been introduced to the organization after the training. However, training and development at TACAIDS faces various challenges including financial resources and lack of clear policies to promptly promote employees once they have finished a certain training. Also, training needs assessment has not been done which results to discretion in allocation of training slots. The researcher recommended that the organization should conduct training needs assessment and gap identification and sponsoring of all training programs should be done. This can be achieved by setting aside a budget for employee training and development and searching for alternative sources of funds without been dependent government sources only.