The main objective of this study was to evaluate the efficacy of a Tier 2 intervention within the context of the Response to Intervention (RtI) model implemented by Spanish first- to second-grade primary school teachers to improve at-risk students' transcription skills. Teachers were instructed in the administration of a writing curriculum-based measure composed of 5 isolates measures (allographs, dictated words with arbitrary spelling or non-ruled, dictated words with rule-based spelling, dictated nonsense words, and dictated sentences) to identify at-risk students and to monitor their progress; and in the implementation of a systematic and explicit instructional program to improve transcription skills in at-risk students. A total of 164 at-risk students from 12 schools from the Canary Islands participated in the study. Teachers were provided with a support system that included a web-based training program for writing. Implementation fidelity was analyzed using direct observations and self-reports. All students were assessed three times during the academic year. In a hierarchical linear growth modeling procedure, differences in growth rates of transcription skills were compared between students who received the intervention, those who did not, and their typically achieving peers. Additionally, the effects of the intervention in the experimental at-risk group were also analyzed, differentiating between those who left the risk status and those who remained at-risk. Children at-risk in the intervention condition appeared to benefit more in handwriting skills than at-risk children in the control condition, but to a lesser extent in spelling accuracy. Nevertheless, improvements in both transcription skills had only been made in the experimental risk group that had left the risk situation.