Abstract: Server-side techniques to selectively compress data for transmission to a client application are described. Characteristics such as the effective transmission rate between the server computer system and a client computer system requesting the data are used to determine if data compression is beneficial. In addition, characteristics of the server computer system such as its processor utilization, for example, may be used to determine if data compression is beneficial. Selective compression in accordance with these techniques provide improved user-responsiveness without the need to install, configure or maintain a client-side application. Accordingly, selective compression in accordance with the invention is particularly beneficial in large, distributed networks in which one or a few “server” computers provide data access service to a large number of “client” computer systems.