Library week is a period set aside for sensitizing the public on the importance of reading, reinvigorating reading habit, and celebrating libraries and the role of librarians and other library workers in transforming the society through effective service delivery. Library and information services are provided by libraries for information, education, research and entertainment needs of people. However, it has been observed that in most developing climes, like Nigeria, the downtrodden like the grassroots and vulnerable are either ignored or not adequately carried along in library scheme of activities. This is so glaring at this point when public libraries in Nigeria are poorly funded, which has profoundly affected the usual services that the grassroots and vulnerable would have benefitted from, such as public library extension services and mobile library services. The paper therefore, advocates that libraries, librarians and library associations through library week can effectively extend library and information services that would impact the lives of the grassroots and vulnerable, as well as improve their decision making capabilities. The paper identified who the grassroots and vulnerable are, enunciated the library services to be extended to them and also discussed the consequences of not extending these services to the grassroots and vulnerable in the society. The study concluded that library week offers opportunities for libraries, librarians and library associations to reach out to the public and interact in such a manner to bring library and information services closer to them, as well as sensitizing them on the need to read and importance of library to their development and growth in all spheres. It is therefore hoped that library week events impact and would continue to positively impact the grassroots and vulnerable. The study also recommended how library and information services can reach and benefit the targeted audience.