The purpose of this study was to assess the influence of ownership structure on collection development practises in private university libraries in South-West Nigeria. The qualitative research design was used in this study. The population consisted of 57 key informants from 31 Private University libraries, including library heads and acquisition librarians. The total enumeration approach was utilized in the investigation. The tool utilized for data collection was a Key Informant Interview. Content analysis was used to examine the data. The findings indicated that collection development practises are influenced by ownership structure, even if the responsibility of purchasing library resources falls on the head of libraries and acquisition librarians. Faith-based institutions have greater levels of collection development practises than non-faith institutions. Participation in collection development was shown to be more favourably connected to joint ownership. The study concluded by stating that the Ownership Structure can help improve collection development practices. Therefore, it recommends that those libraries operating under sole ownership should look for more ownership participation in collection development, notably in financing and budgetary supply.