Vertical wall type structures function as barriers whose purpose is to prevent a material from entering a certain space. Typical applications are embankment walls, bridge abutments, and as underground basement walls. Structural Engineers are responsible for the design of these structures. The loading acting on a retaining wall is generally due to the soil that is confined behind the wall. Various theories have been proposed in the literature, and it appears that all the theories predict similar loading results. In this chapter, we describe the Rankine theory that is fairly simple to apply. We present the governing equations for various design scenarios, and illustrate their application to typical retaining structures. The most critical concerns for retaining walls are ensuring stability with respect to sliding and overturning, and identifying the regions of positive and negative moment in the wall segments. Some of the material developed in Chap. 7 is also applicable for retaining wall structures.