Principals' groups say there is strong opposition to what they say is poor quality training in the Government's national standards in reading, writing and maths.
At least five regional primary principals' associations encourage or support schools that do not attend the training, with their leaders saying it is just not good enough to merit their attendance.
They are Auckland, Canterbury, Mid-Canterbury, Otago, and Southland primary principals associations.
Surveys by the Auckland and Otago associations show 52% of Auckland principals and nearly 64% of those in Otago will not attend any more training.
The Southland and Canterbury associations have not surveyed members, but Southland president Wendy Ryan says its boycott has almost 100% support, while Canterbury president Denise Torrey says many schools there are observing the ban.
However, the Ministry of Education's manager of professional leadership Darren Gammie says 74% of schools are enrolled for more training and most feedback from training already held has been positive.