Schools in areas with low rates of NCEA achievement say they can improve their results by encouraging students to stay at school longer.
In 10 territorial authorities, most of them rural, fewer than 67% of 18 year-olds are achieving level two of the NCEA, compared to a national average of 77%.
Radio New Zealand's education correspondent says many are in the central North Island, in places like Kawerau, Ruapehu, Waitomo, Opotiki and Otorohanga.
Principals say they are changing their curriculums to better reflect their students' interests and a big challenge is persuading teenagers not to leave school for temporary employment.
The Government wants 85% of 18 year-olds to achive at least level two by 2017.