A Word in Season is a language arts instruction curriculum for K-12. The keystone of this curriculum is a four-year high school program that provides an orderly approach to developing language arts skills by integrating western history, literature, and writing.

I have a "friend of a friend" who uses and recommends this but I haven't seen it myself.  Please add a comment if you've used this.  What I can see of it on their website looks thorough and very helpful.

For more information: http://www.awordinseasoncurriculum.com/