DescriptionHigh frequency heart rate variability (HRV) is a measure of neurocardiac communication that is thought to reflect predominantly parasympathetic cardiac regulation. Low HRV has been associated empirically with clinical and subclinical levels of anxiety and depression and, more recently, high levels of HRV have been associated with measures of executive functioning. These findings have informed theories proposing that HRV may provide an autonomic index of a broad, self-regulatory capacity underlying aspects of emotion regulation and cognitive control. This study sought to operationalize and test this proposition using a structural equation modeling approach by examining the relationships of HRV to negative affect (NA) and executive functioning (EF) in a large sample of U.S. adults spanning six decades of age (30s–80s). HRV was modeled as a predictor of an NA factor (self-reported trait anxiety and depression symptoms) and an EF factor (performance on three neuropsychological tests tapping facets of executive abilities). Alternative models also were tested to determine the utility of HRV for predicting EF, with and without statistical control of demographic and health-related covariates. In the initial structural, model HRV showed a significant relationship to EF and a nonsignificant relationship to NA. When covariates were included in the model, HRV’s associations with both constructs were nonsignificant. Age emerged as the only significant predictor of NA and EF in the final model, showing inverse relationships to both. Findings may reflect population and methodological differences between the present thesis and prior research, but they also suggest potential refinements to the interpretations of earlier findings and theoretical claims regarding HRV.