Abstract
The present study aimed at investigating the effectiveness of a differentiated instruction-based program (DIBP) for developing English writing fluency among preparatory schoolers. To do so, thirty students were selected from Fatima Al Zahraa Prep School for Girls, Al-Arish, North Sinai Governorate. For determining the most important and required EFL writing fluency skills for second year prep students, a list of EFL writing fluency skills was designed and validated by a number of EFL jury members. Then, pre and post EFL writing fluency test was designed. Students were pre-tested to determine their entry level of EFL writing fluency skills, then they were taught the program. Data were obtained from administering writing fluency post test. To analyze the data statistically, a paired sample t-test was used. Results of the study revealed that the differentiated instruction based-program had a significantly positive effect on developing the writing fluency skills in English for preparatory schoolers. Recommendations and suggestions for further research were presented.