The theory of metapopulation dynamics now embraces a diversity of spatially structured populations. New and increasingly realistic models address important details of population and community dynamics. But general results are difficult to glean from such realistic models. Discovering the general behaviour of these models will require meaningful comparison of metapopulations with very diverse structures. A simple parameter space can be constructed to facilitate such comparisons. The axes defining this space determine both the structure of metapopulations and the potential for action of various persistence mechanisms. This exercise clarifies the relationship between metapopulation structure and dynamics, and illustrates future research opportunities.