In this study the data was collected from librarians in Tanzania. The purpose was to assess weeding library collection for the sustainable collection development. The study involved the total of 120 librarians from various libraries in the country. The study was purely qualitative by nature. Three specific objectives guided the study: to establish a status of weeding Practice in Tanzania; to identify criteria used for weeding library collection in the study area and to identify challenges facing process of library weeding in a study area. Data was collected through questionnaires and analysed by SPSS. Among other issues the study revealed; lack of weeding library collections, lack of weeding policies guiding library collection; fear of creating spaces without new replacement, lack of funds to procure new replacement; no specific time allocated for weeding collections and the negative perceptions of management towards weeding. The study therefore came up with some recommendations: increasing of budget for acquisitions, need to put more emphasis on the use of electronic resources, needs for libraries allocating specific time for weed, as well as keeping user statistics easily to determine weeding of non-use resources.