Although the Flynn Effect has been studied widely across cultural, geographic, and intellectual domains, and many explanatory theories have been proposed, little past research attention has been paid to subgroup differences. Rodgers and Wanstrom (2007) identified an aggregate-level Flynn Effect (FE) at each age between 5 and 13 in the Children of the National Longitudinal Survey of Youth (NLSYC) PIAT-Math data. FE patterns were not obtained for Reading Recognition, Reading Comprehension, or Digit Span, consistent with past FE research suggesting a closer relationship to fluid intelligence measures of problem solving and analytic reasoning than to crystallized measures of verbal comprehension and memory. These prior findings suggest that the NLSYC data can be used as a natural laboratory to study more subtle FE patterns within various demographic subgroups. We test for subgroup Flynn Effect differences by gender, race/ethnicity, maternal education, household income, and urbanization. No subgroups differences emerged for three demographic categories. However, children with more educated (especially college educated) mothers and/or children born into higher income households had an accelerated Flynn Effect in their PIAT-M scores compared to cohort peers with lower educated mothers or lower income households. We interpret both the positive and the null findings in relation to previous theoretical explanations. (Contains 2 tables and 6 figures.)