Crude oil prices have trended up since the end of the 1990s, peaking at a historic high in mid-2008 that was followed by a steep price correction with a subsequent rebound. This paper considers major forces behind the evolution of the oil price, using a simple model of supply and demand elasticities as a benchmark, highlights implications for inflation and economic activity and draws some conclusions for macroeconomic policy. The analysis suggests that the run-up in crude oil prices since 2003 was due to both vigorous oil demand growth by emerging markets and, from the middle of the decade onward, a weaker than expected oil supply response to rising prices. Prices are unlikely to fall back to levels seen in the first years of the decade either over the short or medium term.