Profesor Stuart McNaughton of Auckland University says giving poor families more money can help reduce educational underachievement.
The OECD says New Zealand has a stronger link between low income and low achievement than the average developed nation.
Profesor McNaughton says intensive school-based programmes can help reduce that link.
But equally good improvements have been found in instances where poor families' incomes have risen.
He says schools cannot be expected to reduce under-achievement alone.