Fine-grained software configuration management offers substantial benefits for large-scale collaborative software development, enabling a variety of interesting and useful features including complexity management, support for aspect-oriented software development, and support for communication and coordination within software engineering teams, described in [4]. However, fine granularity by itself is not sufficient to achieve these benefits. Most of the benefits of fine granularity result from the ability to combine fine-grained artifacts in various ways: supporting multiple overlapping organizations of program source by combining fine-grained artifacts into virtual source files (VSFs); supporting coordination by allowing developers to precisely mark the set of artifacts affected by a change; associating products from different phases of the development process; etc.In this paper, we describe how a general aggregation mechanism can be used to support the various functionality enabled by fine grained SCM. We present a set of requirements that an aggregation facility must provide in order to yield these benefits, and we provide a description of the implementation of such an aggregation system in our experimental SCM system.