The organization sent a letter Tuesday to the 31 school districts it says still retain race-based Indian mascots, logos and team names asking the districts to change them out of respect for tribal nations.
Republican Gov. Scott Walker signed a bill in December making it harder to force public schools to drop tribal nicknames.
Until Walker signed the measure, it took only a single complaint to trigger a state review of the mascot. The school district had to prove the mascot didn't discriminate.
Under the new law, it takes a petition to trigger the review and the burden of proof falls on the complainants to prove the nickname or mascot is racist.