In this essay, we posit that the urban living lab is an object, engulfed in a particular kind of ontological mystique. We show how diverse urban initiatives utilize the label of `lab' strategically, in order to position their practices within the logic of scientific authority and in/exclude different audiences, thus configuring urban participation. The essay links this lab mystique to urban participation by employing the lens of imagineering [van den Berg, 2015], combining imagining and engineering the city in particular participatory configurations. This allows for critical examinations of who is allowed to imagine, experiment and participate in the city through living lab initiatives.