ESL instructors generally use ready-made reading materials in commercially published coursebooks. However, it would be more effective for learners if ESL instructors are involved in developing reading materials for them. This is because they are closer, more sensitive and responsive to the needs of their learners and they are also aware of the reading ability of the learners. ESL instructors can adapt reading materials taken from non-instructional sources like magazines and newspapers and adapt them to suit the needs and reading ability of their learners. Adaptation enables ESL instructors to adjust the difficulty level of the materials. Adjustment can be made by making changes at sentence and word levels and this study intends to demonstrate the structural changes that take place when the materials are being adapted. This study uses the a tool named "IDL Suite" to measure the difficulty level of the materials before and after adaptation.