Epifaunal community development on plexiglas panels was observed over one year. The course ofcolonization is described, and some data are presented on autecology, reproduction, and growth rate ofparticular species. About three months after initial settlement, conditions of coexistence in a mixed barnacle-ascidian community began to change increasingly due to heavy competition for space. The colonial species Botryllus schlosseri proved to be potentially dominant. Shortly before it attained monopolization by replacing barnacles (mainly Elminius modestus), a major physical disturbance eliminated the fast growing ascidian. The roles of physical factors, of biological interactions, and of historical events in community development are discussed in context with succession theory and other concepts evolved more recently. It is concluded that succession-like processes can occur in subtidal fouling communities, but there the existence of a globally stable climax is unlikely. Generally the concept of multistable points seems to be better applicable to marine ecosystems than that of succession in the classical sense.