There is increasing recognition of temperamental influences on risk for psychopathology. Whereas the link between the broad temperament construct of negative affectivity (NA) and problems associated with anxiety and depression is now well-established, the mechanisms through which this link operate are not well understood. One possibility involves interactions between reactive and effortful components of temperament, as well as cognitive factors, like attentional biases to threat stimuli. This study tested a predicted relation between high levels of NA, low levels of effortful control (EC), and an attentional bias toward threat in children. A sample of 104 4th through 12th graders, selected from a larger screening sample because they reported high or low levels of trait NA and EC, completed a dot probe detection task. Results indicated that EC moderated the relation between NA and attentional bias; only children with low levels of EC and high levels of NA showed an attentional bias to threat stimuli. This pattern was not moderated by grade level or age.