It is a frequent observation that individuals differ markedly in their success at voluntary heart rate control. Several dispositional variables have now received attention as possible sources of such individual variation. These are critically reviewed under the following headings: resting and stimulus-elicited heart rate characteristics; autonomic and cardiac perception; imagery vividness; locus of control; trait anxiety. It is concluded that the research on individual differences in cardiac control to date is contributing to a clearer understanding of the mechanisms underlying control. However, for this contribution to be sustained, research needs to service explicit hypotheses about mediating processes. The often arbitrary and atheoretical practices that characterize much of the research in the more general context of individual differences in physiological activity must be avoided.