—We have defined a software component model which specifies components and composition operators. These operators coordinate and encapsulate concurrency between components. In this paper we explain how our model can be used to specify and construct concurrent systems in a hierarchical manner that is amenable to compositional reasoning. In particular, we extend previous work on active components via introducing new, concurrent connectors and show how they can be used together for compositionally constructing concurrent systems. Keywords-active components; concurrent systems; hierarchical composition; compositionality;