A $261 million plan to help the state's struggling primary school students improved their attitude to learning and lifted reading and numeracy levels, but had no "measurable impact" on their year 3 NAPLAN results, a new evaluation of the five-year program reveals.

About 20 per cent of all NSW schools, including public, Catholic and independent, were involved in the program, which targeted communities with the lowest-achieving students in the state. The schools were chosen based on measures including their NAPLAN results and level of disadvantage.

The NSW Literacy and Numeracy Action Plan was introduced to help the state's lowest-achieving young students. Credit:Quentin Jones

The state government launched the NSW Literacy and Numeracy Action Plan in 2012, which included 41,392 kindergarten to year 2 (K-2) students in 448 schools.

"The action plan aimed to increase the literacy and numeracy outcomes for students in the targeted schools, and to reduce the influence of socio-economic status as a key determinant of students' academic performance," an evaluation report into its effectiveness said.