In recent years, libraries worldwide have faced financial constraints that limit their ability to expand and maintain diverse and up-to-date collections. As a result, donation-based resource acquisition has become an increasingly important method of building library collections. This paper explores the role of donations in library collection development, examining both solicited and unsolicited donations, their advantages and challenges, and the legal and policy frameworks that guide their acceptance and management. Drawing on recent literature and case studies, the paper highlights how donations can enhance library resources, particularly in environments with limited budgets. However, it also discusses the potential pitfalls of unsolicited donations, such as irrelevant or outdated materials, and suggests strategies for managing these challenges effectively. Special attention is given to the legal deposit laws, particularly in Nigeria, which provide a formal framework for managing donated and deposited materials. The paper further proposes practical solutions for libraries to improve their donation practices, including the establishment of clear donation policies, donor relations strategies, and the development of endowment funds. The findings underscore the importance of donations in enabling libraries to meet the growing needs of their users, despite financial limitations. Libraries must navigate the complexities of donation management to maximize their benefits while ensuring that resources remain relevant and accessible. This paper concludes that donations are an indispensable strategy in the sustainable development of library collections, especially in resource-constrained settings.In recent years, libraries worldwide have faced financial constraints that limit their ability to expand and maintain diverse and up-to-date collections. As a result, donation-based resource acquisition has become an increasingly important method of building library collections. This paper explores the role of donations in library collection development, examining both solicited and unsolicited donations, their advantages and challenges, and the legal and policy frameworks that guide their acceptance and management. Drawing on recent literature and case studies, the paper highlights how donations can enhance library resources, particularly in environments with limited budgets. However, it also discusses the potential pitfalls of unsolicited donations, such as irrelevant or outdated materials, and suggests strategies for managing these challenges effectively. Special attention is given to the legal deposit laws, particularly in Nigeria, which provide a formal framework for managing donated and deposited materials. The paper further proposes practical solutions for libraries to improve their donation practices, including the establishment of clear donation policies, donor relations strategies, and the development of endowment funds. The findings underscore the importance of donations in enabling libraries to meet the growing needs of their users, despite financial limitations. Libraries must navigate the complexities of donation management to maximize their benefits while ensuring that resources remain relevant and accessible. This paper concludes that donations are an indispensable strategy in the sustainable development of library collections, especially in resource-constrained settings.