The aim of this chapter is to describe issues related to the choice of an optimal design for fMRI experiments. More specifically, it describes how the psychological process of interest is isolated and contrasted using fMRI, and how principal fMRI designs divide into block, event-related, and participant-response dependent designs. The topic of data analysis, with particular emphasis on optimizing and isolating the signal in activated brain regions, is illustrated. Finally, a number of practical matters related to study design are addressed, including optimal sample sizes and trial durations.