Event-related potentials (ERPs) and functional magnetic resonance imaging are both measures of functional brain activation that have been applied to developmental questions. However, the two measures are not identical and reflect different aspects of neuronal function at a physiological level. There is increasing interest in using these methods in combination because of the complementary information they provide about brain activation. ERPs provide more detailed information about the timing of neural activity, while fMRI provides more detailed information about its spatial location. Thus, their combined use may provide more detailed spatio-temporal information than either method alone. In this paper, we review the basic principles of ERP and fMRI and present selected studies from our own work to illustrate their strengths for studies of development. In addition, we discuss the potential benefits and special challenges of the combined use of electrophysiological and functional MRI techniques.