As described in earlier chapters, EEG and fMRI are two powerful, noninvasive tools for studying human brain activity. Since they have complementary spatiotemporal properties, with EEG providing millisecond temporal resolution and fMRI millimetre spatial resolution, there has been a drive over the last two decades to record them simultaneously, a technique referred to as simultaneous EEG–fMRI or simply EEG–fMRI. However, acquiring EEG in the MRI scanner brings additional constraints in terms of setup and signal analysis. In particular, EEG signals are degraded by the variations of the magnetic fields that are central to image acquisition, as well as to cardiac-related pulsations (see the Chaps. 8 and 9). More positively, concurrent acquisition provides new opportunities compared to serial recordings (see Chap. 1), since it allows brain activity to be recorded with the two modalities in the exact same brain state. This is particularly important for spontaneous activities such as epileptic discharges, sleep stages or alpha waves, but also in protocols involving cognitive processes such as memory or attention. It also permits the covariation in single trial fluctuations to be used as a powerful way to link the two modalities. In this chapter, we review the different strategies for acquiring and processing simultaneous EEG-fMRI data in epilepsy, cognition and for spontaneous activity.