We present MSA (Media Services Architecture), a flexible, general architecture for requesting, configuring, and running services that operate on streaming audio and video as it flows through the network. MSA decomposes requested media services into modular processing components that may be distributed to servers throughout the network and which intercommunicate via standard streaming protocols. Use of standard protocols also affords seamless inter- operability between MSA and media content delivery networks. MSA manages media services by monitoring the networked servers and assigning service components to them in a manner that uses available computational and network resources efficiently. We describe some implemented example services to illustrate the concepts and benefits of the architecture. Notes: Copyright IEEE. Published in and presented at the International Conference on Multimedia and Expo 2003, 6-9 July 2003, Baltimore, Maryland 4 Pages