Structuring problems for multi-criteria decision analysis (MCDA) has attracted increasing attention over the past 20 years from both a conceptual and a practical perspective. In this chapter, we describe a set of widely used formal problem structuring tools and how they can be applied to frame and analyze complex decision situations. The following methods are considered: cognitive and causal maps, DPSIR diagrams, scenario planning, stakeholder analysis and SWOT. We also describe how these methods can be combined with MCDA and discuss experiences and challenges related to their joint use.