Some Swedish schools do not identify and support students with reading difficulties efficiently enough during the first years at school. A longitudinal design was used to examine a multitiered RtI-model for identifying and supporting students at risk of reading difficulties in a Swedish school context. The results demonstrated that the RtI-model could be successfully applied. The proportion of students in need of support (i.e., below the 25th percentile) was significantly reduced after two years. Compared to students in the reference group (n  = 759), significantly fewer students in the RtI group (n  = 113) scored below the 25th percentile in word and non-word decoding and reading comprehension in a short text at the end of Grade 2. The discussion highlights the RtI-model’s original ideas.