This paper analyzes the impact of monetary policy during periods of low and high financial stress in the US economy using a Threshold Vector Autoregression model. There is evidence that expansionary monetary policy is effective during periods of high financial stress with larger responses having a higher proportionate effect on output. The existence of a cost channel effect during periods of high financial stress implies the existence of a short run output-inflation trade off during financial crises. Large expansionary monetary shocks also increase the likelihood of moving the economy out of a high financial stress regime.