Objective: The purpose of this work was to find a possible relation between psychosocial risk and any lag or alteration in CNS maturation in a group of children growing up in an economically, socially and culturally disadvantageous environment in a developing country. Methods: A 6 year prospective study of 42 pre-school children, growing and living under psychosocial and economic impediments, is presented. EEGs were previously recorded at different ages: 18–30 months (Int J Neurosci 79 (1994) 213), 4 years (Electroenceph clin Neurophysiol 102 (1997) 512), and 5 and 6 years (this study). The EEG developmental patterns between high- and low-risk children (HRC/LRC) are compared. Results: The EEG pattern in HRC showed higher delta and theta absolute power (AP) and relative power (RP) values in frontal leads, and less alpha AP and RP in posterior leads. The qEEG differences between HRC and LRC diminished with age, although differences in frontal theta and occipital/left temporal alpha bands persisted at 6 years. Conclusions: We conclude that an inadequate or insufficient environmental stimulation is a major contributing factor of the developmental lag in HRC brain maturation. Significance: This is one of the very few longitudinal studies that address the issue of relating sociocultural risk to EEG maturation.