The present study was conducted to investigate into the effectiveness of Computer based Mastery Learning Strategy in IX grade Physics in relation to Academic Stress and Parental Involvement. In a classroom having students with diverse backgrounds, a variety of achievement levels and different learning styles which affects all their ability to acquire knowledge, teachers need to move away from traditional methods of teaching and bring into classroom new and innovative approaches to teach the content. In order to meet the National Education Goal for all the students, Mastery Learning is one of the best reform attempts in the current educational reform movement. A school sample of two hundred and fifty 9^th grade students of high and low Parental Involvement and Academic Stress was drawn from the representative Secondary Schools of Chandigarh. The major findings of the study were:

• The mean gain in Physics through Computer Based Mastery Learning was more than the mean gain through Conventional Group Learning.
• The gain means in Physics of the two Parental involvement groups (High & Low) may not be treated as different beyond the contribution of chance factor and the observed mean difference may be ascribed to chance factor alone.
• The gain means in Physics of the two Academic Stress groups (High & Low) may not be treated as different beyond the contribution of chance factor and the observed mean difference may be ascribed to the chance factor alone.
• The two variables, Instructional Strategies and Parental involvement do not interact to yield different gain means in Physics and the two act as independent of each other.
• The two variables, Instructional Strategies and Academic Stress do not interact to yield different gain means in Physics and the two act as independent of each other.
• The two variables, parental Involvement and Academic Stress do not interact to yield differences in gain means in Physics and they act independent of each other.

The three variables, Instructional Strategies (CBML & CGL), parental Involvement (High & Low) and Academic Stress (High & Low) do not interact to yield different gain means in Physics. The three variables act independent of each other.