The study focused on collection development activities at Mzuzu Prison School Library. It employed social survey research design and used methods to collect data. Nonprobability purposive and convenience sampling were used to sample out 4 librarians and 12 students respectively to participate in this study. The total sample size was, therefore, 16 respondents. Data were collected using a structured questionnaire. Data were analyzed using Microsoft Excel application. The findings in the study indicate that Mzuzu Prison School Library mainly acquires library materials through gift, donations and partially direct purchase. The study has revealed further that the library has collection gaps in academic books such as English language and literature, sciences, and humanities books. However, the collection development activities at Mzuzu Prison School Library are challenged by lack of information resources, financial resources, lack of training for library assistants, inadequate staff, lack of administrative support and lack of collection development policy.