The role of population level processes in determining community dynamics is often ignored. For example, while the role of population density in determining population dynamics is well studied, there have been very few attempts to assess its role at the community level. In this talk, I will give a brief overview of a community-level model of a diverse coral assemblage, where I examined how interactions between species influenced community development. I then move on to an examination of population regulation in adjacent monospecific stands of a zoanthid, showing how density plays an important role in the dynamics of this single species. I will then focus on merging the community and population level approaches to examine how density-dependence influences the dynamics of the diverse coral assemblage. Taking this composite approach, I show that density is important for 38% of parameters in the community model, and in particular it plays a key role in colonisation. Density-dependence also played an important role in allowing high coral cover to develop. It is becoming apparent that density-dependence can play an important role in many communities, and thus it is time for an increased focus on how density-dependence, and other population level processes, influence communities.