This paper investigates whether OECD countries are facing secular stagnation. Secular stagnation is defined as a situation when policy interest rates bounded at zero fail to stimulate demand sufficiently, due to low or negative neutral real interest rates and low inflation, and when ensuing prolonged and subdued growth undermines potential growth via labour hysteresis and discouraged investment. Obtaining firm evidence is complicated by considerable uncertainties surrounding estimates of economic slack and its impact on inflation, crisis-related hit to potential output and neutral interest rates. However, signs of secular stagnation are most evident in the euro area, particularly in the vulnerable members, in contrast to the United States and the United Kingdom, where evidence is less firm. Japan is arguably in the advanced stage of secular stagnation that started almost two decades ago. In countries with symptoms of secular stagnation, more monetary and fiscal stimulus should be accompanied by structural reforms to boost potential growth and neutral rates. Evidence on hysteresis effects strengthens the case for accommodative policies. In general, the large uncertainty about the size and persistence of hysteresis and risks associated with certain measures pose policy dilemmas and call for a comprehensive policy response.