Prices of agricultural and mineral commodities have been rising, with factors like global growth, monetary policy, speculation, and risk playing a role. A new theory suggests that real commodity prices are influenced by global GDP, real interest rates, inventory levels, uncertainty, and the spot-forward spread. While global output and inflation impact commodity prices, factors like volatility, inventories, and the spot-forward spread have the strongest effects. There is also evidence of a bandwagon effect in commodity pricing.