(1) Background: The response to intervention (RtI) model makes possible the early detection of reading problems and early intervention for students at risk. The purpose of this study is to analyze the effective measures that identify struggling readers and the most effective practices of the RtI model in reading in Primary Education. (2) Method: A systematic review of the literature published between 2010 and 2020 was performed, analyzing in the 31 selected articles, the identification and monitoring methods and the interventions at the different tiers of the RtI model. (3) Results: There are different methods to identify struggling readers, and there is no consensus on the matter. There are also many differences in the implementation of the different tiers of the RtI model; however, its effectiveness is demonstrated. (4) Conclusions: The implementation of the RtI model in a flexible way adapted to the circumstances of each moment, and can be considered as a highly effective resource in the prevention and early detection of reading learning problems.