The study was conducted to “Develop and Validate Module in English at Secondary level in Pakistan”. Therefore, the researcher developed a Module consisting of six units on the first five lessons of the textbook of 9 th class. The components of this module were Title, Introduction, Pre-requisite knowledge, Method of study, General objectives, Specific Objectives, Content (Input), Learning activities, Pre-test, Post-test and Feedback. The contents of the module were taken from the first five lessons of the English textbook of class IX. The basic language skills were focused for designing the activities and self-assessment tests of the units. “Introduction" was given at the start of each unit of the module to motivate and brief the students about the task they had to do. General objectives were given at the start of a module and specific objectives were placed at the beginning of each unit of the module. The main objectives of the study were: (a) To develop a sample module from the textbook of English for the 9 th class. (b) To validate a module determining their effectiveness by teaching in the classroom. (c) To validate module determining their effectiveness from the performance of low and high achievers in the classroom. The module was validated by conducting lessons in the classroom with its help. Therefore, the Pre-test Posttest were used as the instruments of the study. The Pre-test was used to find out the competencies of the students to deal with the material presented in the module. The validation of the module was checked by administering the same pre- test as a post-test to the subjects of both experimental and control groups by changing the arrangement of the items on the pattern of “Even Odd Numbers”. The module consisting ivof six units were taught in 14 weeks and it consumed 80 hours of the students for solving the activities given at the end of the module. The students of secondary classes studying in Government public secondary schools were the population of study. The control group as well as the experimental group was of equal size, each having 30 students of 9th class. The scores of pre-test and post-test were the data of study. The significance of difference between the scores of groups at 0.05 levels was tested by applying t-test and analysis of variance. The study proved that the material designed as a module promoted independent learning habits in the learner, provided opportunity to proceed at his own pace, ensured active participation, useful for slow as well as of bright students, enabled the students to comprehend difficult concepts, and kept them on the track. For this purpose, it was recommended that the policy makers should take steps for the development and validation of modules at secondary school level and the teacher training institutions should take steps for the training of the teachers for the development and validation of modules in different subjects. Textbook board may arrange workshops for writing of the books on modular pattern and the school libraries should be enriched with the books on the topics of development and validation of modules. The subject specialists and senior teachers should be trained to revise and update the modules in the light of modern researches on continuous basis. In spite of the fact that the material developed as a module under this study proved valid as a result of better performance of the students in the experimental group. However, there is also need of further studies on this topic by controlling some other variables such as attitude of the students, level of intelligence, timing of work that may influence the performance of the students.