The aim of this study is to determine how the absence of a collection development policy is affecting collection development practices at Mzuzu University Library. This research is a case study that makes use of a sequential mixed design which means that data was collected in a number of stages. The researchers personally collected data from the field using a semi-structured questionnaire, tape recorder, and coding schedules. The main data collection procedure was a focus-group discussion involving senior library members of staff. Researchers also carried out physical inspection and analysis of books from the Acquisitions Department, and Reading Area. Qualitative data collected was analysed thematically, whilst quantitative data was analysed using MS Excel. The study found out that the absence of a collection development policy has greatly affected collection development practices at Mzuzu University Library. Most of the core collection development practices such as selection, acquisition, weeding and preservation were haphazardly done as there were no clearly documented guidelines to guide the various individuals that were involved in the implementation of these collection development tasks to ensure consistency. The findings of this study are significant because they could be a catalyst for the development of collection development policy at Mzuzu University Library, which might in the long run provide solutions to collection development challenges which the institution currently faces.