Dynamic caching policies and/or dynamic purging policies are provided for modifying the entry and eviction of content to the cache (e.g., storage and/or memory) of a caching server based on the current and past cache performance and/or demand. The caching server may modify or replace a configured policy when cache performance is below one or more thresholds. Modifying the caching policy may change caching behavior of the caching server by changing the conditions that control the content that is entered into cache or the content that is deferred and not entered into cache after a request. This may include assigning different probabilities for entering the same content into cache based on different caching policies. Modifying the purging policy may change eviction behavior of the caching server by changing the conditions that control the cached content that is selected and removed from cache.