Although entitled ‘Design of single piles’, this chapter deals mainly with the analytical methods used in design, rather than with the actual design process. Practical and economic factors play an essential role in choosing the type and relative size of pile for a given application. For each pile considered, analysis is then required in order to assess whether that pile will satisfactorily fulfill its function as a foundation element. This analysis will generally involve calculation of the ultimate capacity of the pile under working load conditions, and an assessment of any other potential problems, for example, whether the pile can be installed with a given size of pile driving rig.