Electrophysiological activity at rest reliably differentiates healthy individuals from neuropsychiatric populations, including SZ and BP (Barry et al. 2003; Thibodeau et al. 2006). Importantly, resting state EEG has been indirectly linked to variations in cognitive task performance (Stam et al. 2002; Finnigan and Robertson 2011); moreover, EEG synchronization appears to support the communication between distinct neural regions which may facilitate coherent cognition and behaviour (Varela et al. 2001; Ward 2003). Therefore, disruptions in resting EEG may indicate disturbances in neural interactions that support cognition and arousal in the absence of task-related activity. In this study, the utility of resting EEG measures in characterizing and distinguishing SZ and BP was evaluated.