To verify wheter development of cognitive skill and peer acceptance are necessarily linked, 212 students of low socioeconomic status in the first, second, and third grades of a public school in Brazil were studied. A sociometric evaluation of peer group acceptance in play and study situations was conducted. The cognitive tasks where the mental imaging and conservation of mass and length (operative task) as well as location of dice and equidistancing arrangements (creation of possibilities tasks). Analysis showed the children identified as desirable study companions had highly developed general cognitive abilities, and those chosen as desirable for both, study and play not only had highly developed general cognitive abilities but also highly developed operativeness. Children who were socially isolated, however, had even higher mean cognitive assessment score in relation to both creation of possibilities and general cognitive development than did those with ratings of negative or positive salience.