The last decade has seen an explosion of research in macroecology. This is evidenced by the rapid increase in the number of publications which contain the word macroecology in their title, abstract, or key words, or which cite seminal publications. The promise of macroecology is that very general statistical patterns provide clues to the operation of equally general mechanistic processes which govern the structure and dynamics of complex ecological systems. There has been much progress in characterizing macroecological patterns and showing that they hold across different taxonomic and functional groups of organisms, kinds of environments, and geographic regions. There has been much less progress, however, in identifying the underlying mechanisms. The challenge for the future is to build and evaluate mechanistic models which can explain macroecological patterns in terms of established physical and biological principles.