Abstract: The United States’ wars in Afghanistan and Iraq have revived again the phenomenon of “regime change” that was thought to have died with the Cold War. We study Cold War “regime changes” for insight, although of course they do not extrapolate exactly to modern events. The recent declassification of Cold War documents now makes it possible to develop a new time series cross section dataset of superpower interventions during the Cold War which takes account of interventions by the secret services. We find that US interventions to prop up a leader are associated with significant short term and medium term declines in democracy in the intervened country. We observe a similar size effect for Soviet interventions, but they are not robustly significant like US interventions. Although the negative effect of interventions dissipates once the intervention ends, an intervention has a large effect on democracy when it lasts for a long time.