Objective: Sluggish Cognitive Tempo (SCT) is a controversial Attention Deficit Hyperactivity Disorder (ADHD) subtype that has been proposed to manifest as inattention, excessive daydreaming, “fogginess,” and lethargy. The current study examined the link between this constellation of inattentive symptoms in early childhood and executive functioning (EF) and processing speed (PS) in early adulthood in a non-ADHD sample. Method: A diverse group of neurologically healthy young adults (N = 108) was evaluated on measures of EF and PS (BADS, Key Search Test; Symbol Digit Modality Test [SDMT]; D-KEFS, Color-Word Interference Test [CW]). SCT and ADHD subscores were derived using a subset of items from the Wender Utah Rating Scale (WURS), a retrospective measure of childhood ADHD symptoms. Results: Correlational analyses found that WURS SCT symptoms were related to Key Search time (r = −.35, p = .05) or WURS ADHD score discounting SCT items (p > .05). After covarying for IQ (Test of Premorbid Functioning), hierarchical regression analysis revealed that childhood SCT symptoms significantly predicted Key Search time (ß = −.32, p < .05), but not CW inhibition time (ß = .12, p = .23). Conclusion(s): In a non-ADHD sample, childhood SCT symptoms are uniquely correlated with several measures of EF (e.g., planning efficiency) and PS in adulthood. The findings provide preliminary evidence for SCT as a distinct cognitive phenotype that may exist independently of ADHD.