Theory: Democratic accountability requires that the public be reasonably well-informed about what policymakers actually do. Such a public would adjust its preferences for ''more'' or ''less'' policy in response to policy outputs themselves. In effect, the public would behave like a thermostat; when the actual policy ''temperature'' differs from the preferred policy temperature, the public would send a signal to adjust policy accordingly, and once sufficiently adjusted, the signal would stop. Hypotheses: In domains where policy is clearly defined and salient to the public, changes in the public's preferences for more policy activity are negatively related to changes in policy. Methods: A thermostatic model of American public preferences for spending on defense and a set of five social programs is developed and then tested using time series regression analysis. Results: Changes in public preferences for more spending reflect changes in both the preferred levels of spending and spending decisions themselves. Most importantly, changes in preferences are negatively related to spending decisions, whereby the public adjusts its preferences for more spending downward (upward) when appropriations increase (decrease). Thus, consistent with the Eastonian model, policy outputs do ''feed back'' on public inputs, at least in the defense spending domain and across a set of social spending domains.