In November 2008 at Purdue University, the 2nd Workshop on Human Problem Solving was held. This workshop, which was a natural continuation of the first workshop devoted almost exclusively to optimization problems, addressed a wider range of topics that reflect the scope of the "Journal of Problem Solving." The workshop was attended by 35 researchers from around the world. The program of the workshop is available at: http:// spiderman.psych.purdue.edu/problem_solving/workshop08/. There were two full days of talks and posters, covering insight, education, decision making and causality, combinatorial optimization and applications. The level of excitement was high, and the lively and informative discussions confirmed that, despite the fragmentation of the field, there is something special and unique about problem solving that is likely to help define the field, almost exactly 100 years after the Gestalt Psychologists established it for the first time. Defining the field is obviously important, but doing solid research and disseminating the results is absolutely critical. This special issue provides a nice sample of the current work on human problem solving illustrating a variety of experimental tools and conceptual frameworks.