This study explores the successes and challenges of the virtual space component of the 21st Century Learning Labs in Libraries and Museums funded by the Institute for Museum and Library Services (IMLS) and the MacArthur Foundation. This study synthesizes the literature on informal learning for youth that motivated these learning labs and analyzes existing evaluative approaches to public library initiatives. The author adopts a grounded theory approach and conducts semi-structured interviews with learning lab staff from four sites that received the 21st Century Learning Labs in Libraries and Museums Grant. Key concepts from the literature guide the analysis of the interviews to produce a foundational evaluative framework that can be used by public library staff to design and evaluate goals for their virtual learning lab. This framework considers both the overall mission of virtual learning labs and contextual factors that influence the library.