Abstract \\r\\nThis study examined management capacity building practices for librarians’ effective sservice delivery in federal university libraries in South South and South East Nigeria. The study was specifically aimed at determining existing management capacity building practices, the extent to which the existing capacity building practices contribute to effective service delivery, challenges associated with management capacity building practices, and strategies for enhancing management capacity building practices in federal in federal university libraries in South East and South South Nigeria. The study adopted descriptive survey research design. The total population that was used for this study was two hundred and eighteen professional librarians (218). Data was collected using questionnaire and interview schedule. A total number of one hundred and seventy eight (178) copies of the questionnaire were correctly filled, returned and used for this study. Data collected were analyzed using mean scores and standard deviation. The results reveal that management capacity building practices exist in these libraries such as mentoring, effective communication from top to down, giving people opportunity to contribute in the library vision and mission, and creating opportunity to develop adequate skills. Result also shows that challenges confronting management capacity building practices include; inadequate funding, erratic electricity supply, poor maintenance culture, poor collaborative practices between libraries. The researcher recommended among other things that librarians should be willing to embrace new trends in service delivery, libraries should recruit qualified staff, libraries need to be adequately funded, ICT skills need to be developed, modern ICT facilities should be provided, and there should be adequate support for training, among others.\\r\\n