In 2015, a report of a literature review to The NSW Government sector in Australia, from the Centre for Education Statistics and Evaluation (D Bradford and W Wan), stated Reading Recovery improved short term reading outcomes among the poorest performing readers, the primary intention of the intervention.
Reading Recovery: A Sector-Wide Analysis

Australian Council for Educational Research (ACER) in 2013 also reports there are numerous studies showing the significant positive effect of Reading Recovery overall when comparing  Reading Recovery to other interventions, having substantially higher effect sizes, on average, than the three other highly effective programs analysed.  Most of the sixteen interventions reviewed originated in Australia and the majority have been implemented, at least to some extent, in NSW schools. A small number of internationally developed interventions were included in the review because the intervention was widely implemented in either Australia or New Zealand. (e.g. Reading Recovery. NZ)
Literacy and numeracy interventions in the early years of schooling : a literature review : report to the Ministerial Advisory

In the Kimberley Sharratt Hayes & Coutts. (2015) report on a study involving Reading Recovery teachers assisting students in a population where 44 percent are First Nations’ Peoples and were requiring the most support to develop literacy skills. Not only were the earliest struggling learners brought quickly to reading and writing, the implementation of Reading Recovery in this region offered additional substantiation of the cost-effectiveness of this early intervention for a school system.  A trained Reading Recovery teacher on staff had a professional sphere of influence on the learning and teaching of the whole school community.

In 2019 New Zealand evaluated the impact of Reading Recovery in the 58% of all NZ schools where it was implemented and found it was an effective intervention (Appleton-Dyer, Boswell & Reynolds. 2019) for the target group of having low -literacy levels for their age.

In a report to the New Zealand Ministry of Education by NZCER (2005) it was found that Reading Recovery intervention was effective for most students. Maori and Pasifika students entered Reading Recovery with lower initial scores; these differences were reduced by the time the series of lessons ended. McDowall, S., Boyd, S., & Hodgen, E. with van Vliet, T. (2005).

A report to NSW Ed. Dept of a Review of literature (Bradford & Wan CESE  2015) found Reading Recovery is an “effective intervention improving short term reading outcomes among poorest performing readers, which is the intention of the intervention.” (pg 21)

The NSW Director of Catholic Education Office Sydney, Dr. Dan White reports in media of the successful outcomes for Sydney Catholic Schools.  (Bagshaw & Smith 2015)