Decision structuring, also known as decision framing, provides the foundation and roadmap for analyzing a decision. For decisions that warrant a systematic approach, structuring begins with identifying the problem for analysis, which sounds simple but can be deceptively difficult because decision problems are often ill-formed at the start. Many have worked on a problem, alone or with others, only to realize down the road that it’s the wrong problem, which Ron Howard calls an “error of the third kind”. How a decision is framed, e.g., narrowly or broadly, can have a profound effect on subsequent analysis and solution. Tools and templates are available to get started, but perhaps no technique is more essential that simply taking the time to ponder on what the problem is all about. Structuring is an iterative process, which allows complexity to be added as needed because not all decisions need the full Monty analysis. All of the case studies in this book have gone through decision structuring and most followed an iterative, prototyping process. In particular, the case studies in Section I highlight the value of decision structuring to uncover hidden assumptions hindering a good solution and to figure out the scientific information needed to find a good solution.