This talk explores “critical spatial practice”, a term I introduced in 2002 to refer to urban interventions that transgress the limits of art and architecture to engage with the social and the aesthetic, as well as the interstitial spaces between public and private. Critical spatial practice draws attention to the critical, but also the specifically spatial aspects of interdisciplinary processes operating between art and architecture. I discuss projects by practitioners muf and transparadiso, before reworking critical spatial practice for today, making reference to the performative and the temporal. I describe how performing interpretations of critical spatial practice through a situated criticism gave rise to my current practice of “site-writing”. A reading of May Mourn, a text-work which deals with the history of welfare state architecture, taken from my new book on transitional spaces, concludes by addressing the current London housing crisis.