While scientific reasoning is mostly guided by disciplinary traditions, transdisciplinary research rests on other cognitive strategies. As it does not have a ready-made stance toward problems, figuring out what the puzzle is and what the answer might look like are crucial aspects of transdisciplinary inquiry. Through examples from environment and sustainability studies, the volume discusses heuristic schemes that can give structure to this exploration. By focusing on heuristics, rather than on methods, concepts, or general guidelines, the book argues that a problem-centered approach often resists the rigor of methodology. Learning from experience provides valuable “rules of thumb”, checklists, and other cognitive schemes for making ill-defined problems more tangible. Written by an international team of authors, the chapters draw examples from dealing with issues in environmental protection, transport and climate policy, ecosystem services and disservices, environmental beliefs and attitudes, and more. Together with more theoretically oriented chapters, they show that the intellectual processes needed to tackle complex sustainability problems are as much about heuristic problem solving as they are about methodical work.