Under the present invention, when a request for a web page is received from a client on a server, the web page is built and analyzed for cacheability. If the web page is cacheable, an entity tag is generated. The entity tag generally identifies the various sources of dynamic content in the web page, and includes cacheability flags and time values associated with the dependencies. The entity tag is sent to the client with the web page where it is stored in local cache memory. If a subsequent request for the same web page is issued from the client, the request is accompanied with the entity tag (e.g., in a header). The entity tag is decoded and analyzed by the server to determine whether the cached web page is still valid.