Only theories based on factual evidence may now be taught in California's public school science classes. Theories such as "creation science," based upon religious beliefs, may be taught in "history-social science and English-language arts curricula," but not in science classes.

The move will have national impact, as California commands such a large share of the textbook market that textbook publishers will accede to the state's wishes.

The board also moved to encourage textbook publishers to treat evolution like other scientific topics and to remove phrases that suggest that evolution is "only" a theory.