Despite the growing popularity of using living labs as an innovation platform, little is known about their characteristics. This research uses a case study approach with content analysis to identify a list of key attributes that help define the concept of living labs. Drawing upon the literatures on user innovation, co-creation, and living labs, theoretical constructs were used to guide the investigation of living lab applications that are publically available through the European Network of Living Labs (ENoLL) website. The results from the research produced nine constructs that give insight into living labs. These constructs reflect both qualified pre-existing notions and disqualified notions of living labs, such as the objective, the degree to which users are involved, and the legal structure for operations. They bring about significant new knowledge regarding the nature of living labs, including their modes of communication, their purposes, handling of intellectual property, and generation of funds.