While longitudinal studies of children treated for brain tumors have consistently revealed declines on measures of intellectual functioning, greater specification of cognitive changes following treatment is imperative for isolating vulnerable neural systems and developing targeted interventions. Accordingly, this cross-sectional study evaluated the performance of childhood brain tumor survivors (n = 50) treated with conformal radiation therapy, solid tumor survivors (n = 40) who had not received central nervous system (CNS) -directed therapy, and healthy sibling controls (n = 40) on measures of working memory [Digit Span and computerized self-ordered search (SOS) tasks]. Findings revealed childhood brain tumor survivors were impaired on both traditional [Digit Span Backward- F(2,127) = 5.98; p < .01] and experimental [SOS-Verbal- F(2,124) = 4.18; p < .05; SOS-Object- F(2,126) = 5.29; p < .01] measures of working memory, and performance on working memory measures correlated with intellectual functioning (Digit Span Backward- r = .45; p < .0001; SOS- r = -.32 to -.26; p < .01). Comparison of performance on working memory tasks to recognition memory tasks (computerized delayed match-to-sample) offered some support for greater working memory impairment. This pattern of findings is consistent with vulnerability in functional networks that include prefrontal brain regions and has implications for the clinical management of children with brain tumors.