The Arab World is fortunate to have large endowments of oil and gas. The level of endowments across countries of the Arab region varies: the Gulf states which have massive endowments and small populations, and other states which have more moderate endowments and much larger populations. I will refer to the latter as Middle-Income Middle-East States (MIMES). These differences in resource endowments have implications for both the decision as to how much of resource revenues should be saved, and how much of the savings should be invested domestically. In this chapter, the author discusses principles and rules for saving and investment appropriate to the GCC and MIMES