Contemporary research indicates that brain development occurs during childhood and into early adulthood, particularly in certain regions. A critical question is whether premature or atypical hormone exposures impact brain development (e.g., structure) or function (e.g., neuropsychological functioning). The current study enrolled 40 girls (aged 6–8 years) diagnosed with premature adrenarche (PA) and a comparison group of 36 girls with on-time maturation. It was hypothesized that girls with PA would demonstrate lower IQ and performance on several neuropsychological tasks. The potential for a sexually dimorphic neuropsychological profile in PA was also explored. No significant univariate or multivariate group differences emerged for any neuropsychological instrument. However, effect size confidence intervals contained medium-sized group differences at the subscale level. On-time girls performed better on verbal, working memory, and visuospatial tasks. Girls with PA showed improved attention, but not a sexually dimorphic profile. These results, though preliminary, suggest that premature maturation may influence neuropsychological functioning. (JINS, 2012, 18, 151–156)