This study details the creation of a four-tiered format designed to help preservice teachers write differentiated lesson plans. A short history of lesson plan differentiation models is described and how the four-tier approach was developed through collaboration with classroom teachers and university faculty. The unifying element for the format came from response to intervention. Inservice teachers experimented with the format and identified missing elements. Extensive data were gathered when the method was pilot-tested by a preservice teacher. Further data collections were made when graduate preservice teachers used the four-tier method. This collaborative process helped create a four-tiered format for lesson differentiation designed to help preservice teachers create lesson plans to engage all students in the learning process.