AbstractThis study evaluates the reliability of profile analysis for assessing differential abilities on the McCarthy Scales for Children's Abilities (MSCA). Subjects were enrolled in private schools and ranged in age from 5–5 to 6–5. The test‐retest interval ranged from 3 to 6 weeks, with a mean interval of 24 days. Results indicated 70.9% of the sample showed profile variability not reasonably accounted for as real fluctuations in measurable abilities. General application of the null hypothesis procedure for calculating statistical significance of scaled score differences as a basis for interpretive judgments is disc