This paper concerns the role of accidents and generative processes in design. It discusses two studio projects carried out at the University of Auckland School of Architecture and Planning in 2006. ‘Accident’ called for the design of a vehicle depot as a place for chance meetings and failures to connect. ‘Emergency’ called for the design of an emergency facility. Both projects were intended to provoke students to consider the unintentional, serendipitous and disastrous aspects of designing. In initial discussions, accidents were commonly understood as exceptions to the norm, failures of a system, or loss of control. Against this view, students were presented with concepts from emergence theory, and Paul Virilio's argument that accidents are inherent in systems. In response, students opened up what this paper describes as 'risky intervals', strategies for exposing their design to the unintentional.