20% of my portfolio is foreign stocks (VXUS). It amounts to 25% of my total stock allocation. I primarily do that because of diversification and non-correlation with my primarily US Stock allocation. That non-correlation I reckon is getting lower especially when global macroeconomic events are the main factors driving many day's price movements. Before moving to this position I debated quite a bit about the merits of international stocks. Bogle and Buffett prefer US stocks and I know Bogle routinely admonishes people to keep away from international. My thoughts are that while the US is the biggest most dominant nation on the earth right now, with the largest and one of the most free markets, holding a somewhat small position outside the US won't significantly diminish returns while providing additional insurance in case things don't work out as planned in the US. Case in point, US and Western European growth is significantly slower compared to previous years, along with unfavorable demographic developments (including Japan) I think growth will not pick up to pre-crisis levels for some time, possibly for a very long time. Holding some stock outside the US to capture some of the gains of other nations who may grow more than us is worth the risk for me, in fact I find it risky to hold all US stock given those conclusions.