I went with 15% international developed market, 5% emerging market, 7% reits (lower because I own a house which is real estate), 20% bonds divided up into inflation protection and treasury index, and the rest US stock market index. I don't think there's any one right answer, and as my thinking and reading on this issue evolves so will the asset allocation. Also the science of investing will come up with new ideas and I want to remain open to those. My international stock index funds are mainly a mix of total international index, and some emerging market index.