Single piles such as signposts and lampposts and pile groups that support bridge piers and offshore construction operations are constantly subjected to significant natural lateral loads (such as wind loads and wave induced loads) (Figure 8.1). Lateral loads also can be introduced on piles due to artificial causes such as ship impacts. Therefore, the lateral load capacity is certainly a significant attribute in the design of piles under certain construction situations. Unlike in the case of the axial load capacity, the lateral load capacity must be determined by considering two different failure mechanisms: (1) structural failure of the pile due to yielding of pile material or shear failure of the confining soil due to yielding and (2) pile becoming dysfunctional because of excessive lateral deflections. Although passive failure of the confining soil is a potential failure mode, such failures occur only at relatively large deflections that generally exceed the tolerable movements. One realizes that “short” piles embedded in relatively stiffer ground would possibly fail because of yielding of the soil, whereas “long” piles embedded in relatively softer ground would produce excessive deflections. In view of the above conditions, this chapter is organized to analyze separately the two distinct issues presented above. Hence, the discussion CONTENTS