The association of personality with resting state networks has been investigated in the mature brain, but its development has not been investigated, particularly in longitudinal design. Besides, all existing evidence is obtained using functional magnetic resonance imaging and there are no data on electrophysiological underpinning of these associations. We have acquired three yearly recordings of resting state EEG data in primary school children. Parental ratings of child's personality were obtained in the third wave. Seed-based oscillatory power envelope correlation analysis in conjunction with beamformer spatial filtering were used to obtain electrophysiological signatures of the default mode network (DMN) associated with self-referential processing and the central executive network (CEN) related to the control of attention. Analysis showed that in alpha frequency band, developmental changes in the balance between DMN and CEN in frontal cortical regions involved in the representation of affective value of primary reinforcers predict parental ratings of positive personality traits captured by the general factor of personality. Latent growth curve modeling showed that relative increase of outward directed attention associated with CEN in the first school year underlies the development of positive personality traits during this developmental stage.