Studies of foraging behaviour have proliferated over the past 30 years. Two schools of thought have emerged, one focusing on theoretical aspects (so-called 'optimal foraging theory'), the other on empirical studies. We summarize both, showing how they have evolved and begun to coalesce during the past decade. The emerging new framework is more complex than previous models, combining theory with observation. Modem phylogenetic methods promise new insights into how animal foraging has evolved.