Manuscript search flow diagram. Articles were excluded during the eligibility phase if they did not meet any of the following criterion: 1) Participants identified with or at risk for reading difficulties, 2) Participants enrolled in kindergarten through third grade (or ages five to nine), 3) Intervention targeted early literacy in English, provided between 15–99 sessions, and was not part of the general education curriculum, 4) Research design included experimental, quasi-experimental, or single subject designs that demonstrate experimental control (AB designs excluded), 5) The dependent variables addressed reading outcomes related to reading.