The present research approaches differentiated instruction in light of metacognition and collaborative practices. The aim is to examine the contribution of a Tier 2 intervention implemented by teachers through a program entitled The Strategic Planners of Writing to the writing performance of 3rd and 4th grade students with writing difficulties. The special teachers and 31 students who received special education services in inclusive classes at eight public primary schools in the prefecture of Attica in Greece were randomly selected. Sixteen students in four inclusive classes participated in the intervention program and formed the experimental group. Fifteen students in another four inclusive classes received regular classroom instruction from their special teachers and formed the control group. The teachers of the experimental group received intensive practice in specific strategy instruction and collaborative practices in a differentiated teaching environment such as that of the Tier 2 Response to Intervention Program. The students were evaluated before and after the end of the intervention regarding the general quality of the written narratives they produced and the metacognitive knowledge they possessed about writing. The experimental group received an 8-week intervention with a frequency of two lessons per week. The teachers followed the structured lesson plans and applied educational material given to them according to the stages of the Self-Regulated Strategy Development model. The results indicated that the experimental group showed statistically significant improvements in text structure and in the general quality of the produced narratives compared to the control group. At the same time, it was found that there was a statistically significant difference in the experimental group's awareness of the planning phase of the writing process and structural elements of a good narrative text compared to that of the control group.