Active aging is important to older adults through social engagement with others and connection with the community. Social engagement aligns with the concept of ‘third place’ which is defined as ‘a social infrastructure in a public setting for informal gatherings’, such as library, park, and commercial places. In this project, three libraries in Victoria were selected as case studies for addressing the research question of identifying factors of third places that support active aging for social engagement in Victoria. Through qualitative observational study and quantitative questionnaire survey, this study has identified the key factors that motivate older adults to visit the library for social interaction, which are: user-friendly service with nice and friendly staff, location, accessibility, safety, visual connectivity and wayfinding. Based on the findings, libraries serve as an important third place among older adults in Victoria.