It has been 40 years since Berkeley Professors Horst Rittel and Melvin Webber articulated the concept of "wicked problems," problems that are challenging because they are ill-defined, complex and constantly changing. In their seminal article in Policy Sciences, they argued that the profusion of wicked problems throughout social policy domains such as urban design and city planning posed dilemmas for the scientific approach to problem-solving, which was developed to deal with "tame" problems. The notion of wicked problems is still widely embraced by designers and policy makers working on issues ranging from climate change to healthcare reform. Yet this formulation, rooted in modernism and emphasizing positivist science and technology, has been subsequently challenged by alternative epistemological approaches such as Marxism, feminism, and post-structuralism. The Wicked Problem SYMPOSIUM on Saturday, October 26, will critically interrogate the history and evolution of Rittel and Webber's idea of the "wicked problem," and appraise the utility of wicked-problem thinking in the light of contemporary issues of significance to society from a broad and interdisciplinary perspective. The related WORKSHOP, on Sunday, October 27, will address the more specific topic of Rittel and Webber's work as it pertains to the issues of urban and regional sustainability, and will feature talks that will later be featured as papers in an accompanying issue of the journal Landscape and Urban Planning (LAND). The extended conference is jointly organized by the College of Environmental Design (CED) at the University of California, Berkeley, the Global Institute for Urban and Regional Sustainability (GIURS) at the East China Normal University, Shanghai, and LAND. Judith Innes, CED Bryan Norton, Georgia Tech Brian Head, University of Queensland, Australia Panel discussion/questions