AbstractThe focus of the present study was to examine the stability of the McCarthy Scales of Children's Abilities for a sample of 42 English‐speaking and 42 Spanish‐speaking Mexican‐American preschoolers of low SES background. The subjects were retested after a period of one year, and a test‐retest stability coefficient of .88 was observed for the General Cognitive Index for the English‐speaking children and .77 for the Spanish‐speaking children. It was concluded that the results of the present study provide some preliminary evidence that the McCarthy is a relatively stable instrument for English‐speaking Mexican‐Am