Cognitive development of children depends on nutritional and socioeconomic factors. The objectives of the present study were to assess the cognitive development and to investigate the relationship of nutritional and socioeconomic status (SES) to cognitive development in 5-12 year old Santal children of Purulia district of West Bengal, India. The nutritional status of each child was assessed by z-score of height-for-age, weight-for-height and weight-for-age parameters. SES was measured using the updated Kuppusswami scale. Cognitive development was measured by Raven's Coloured Progressive Matrices (RCPM). The growth curve of RCPM scores of Santal children remained around the 5(th) percentile values of British children. The RCPM scores of the adequately nourished children and upper-lower SES were significantly higher (p < 0.05) than the children with lower SES and nutritional status. About 42.96% and 27.69% of Santal children were found to be in the intellectually deficient and below average groups, respectively. RCPM scores of Santal children were significantly correlated with nutritional status and socioeconomic factors (p < 0.01). The surveyed children showed poor cognitive functions. The vulnerable nutritional and socioeconomic statuses of Santal children are the major causes for their poor cognitive development.