The major purpose of the study was to identify the impact of teachers'' instructional practices, delineated in TARGET Model, on achievement goal orientation of secondary school students in the subject of mathematics. In order to develop the rationale of the study, a survey was done to identify the relationship between mathematics teachers'' instructional practices and achievement goal orientations of students at secondary school level. Afterward an experiment was devised to endorse mastery-approach goal orientation among secondary school students through instructional practices prescribed in TARGET model. To assess the impact of these instructional practices on achievement goal orientations of students, a follow up test was administered after six months of the endorsement and sustainability of endorsed orientations was assessed. The target population of the study was secondary school students enrolled in government schools in the province of the Punjab. The sample of the survey comprised 874 students (Boys = 428, Girls = 446) of class 9th, which was selected through multistage stratified sampling technique from nine districts of the Punjab on the basis of education deprivation indices of these districts. Sample of the experiment comprised one whole randomly selected section of class 9th, science group containing 48 students. Two matched groups (control and experimental) each consisting 24 students, were made on the basis of students'' scores in pre-test. Sample of the follow up test, to assess the impact of the treatment, comprised the students of experimental group only. A questionnaire “Achievement Goal Orientations and Perceptions about Teachers'' Instructional Practices Questionnaire (AGOPTIPQ)” was used to collect data for the survey. The questionnaire consisted of two sets of questions: one set to measure students'' achievement goal orientations "Achievement Goal Orientation Questionnaire AGOQ)" and the other one to know students'' perceptions about instructional practices (related to six factors of TARGET vi model) of their mathematics teachers "Perceptions about Teachers'' Instructional Practices Questionnaire (PTIPQ)". AGOQ was used for pre-test, post-test and follow-up test. For experimental group the treatment comprised lesson plans of seven chapters of mathematics text book for class 9th for a period of thirteen weeks (one term). All the aspects of TARGET Model (Task, Authority, Recognition, Grouping, Evaluation and Time) were addressed in lesson plans to make mastery goal endorsing classroom environment. Lesson plans were validated by two mathematics teachers. A Mathematics Achievement Test (Containing 70 MCQs) of taught units was used to measure the effect of treatment on students'' achievement in the subject of mathematics. A pilot study was conducted to validate the instruments. Reliability indices (Cronbach Alpha) of the questionnaires PTIP and AGOQ were 0.844 and 0.76 respectively, which are statistically significant. Confirmatory Factor Analysis was done to assess the factor loading of the statements. The reliability index of the final mathematics achievement test was 0.87 (Cronbach Alpha). Analysis of the data showed that at secondary level students had greater performanceapproach goal orientation mean score (M = 2.40, SD = 0.65), than they had masteryapproach goal orientation mean score (M = 2.26, SD = 0.62). Analysis also revealed that teachers'' instructional practices were more performance-approach goal endorsing than masterapproach goal orientation. Analysis also showed that AGOs of students were significantly correlated (r = 0.249) with instructional practices (described in TARGET model) of mathematic teachers. Analysis of experimental data showed that treatment made a significant difference in mastery-approach goal orientation of students. Mean gain scores of control group (M = .35, SD = .58) and experiment group (M = -.98, SD = .94), t(46) = -5.94, p <.05, were statistically significantly different. Difference between mean gain scores of control and experimental groups for other three goal orientations were not statistically significant. Results also showed that treatment enhanced the achievement level of experimental group in mathematics. The difference between mean achievement scores of experimental (M = 77.92, vii SD = 7.29) and control group (M = 69.33, SD = 9.79) were statistically significant. Analysis revealed that there was no statistically significant difference between mean scores of students of experimental group in post-test (M = 3.71) and follow up test (M = 3.58) on masteryapproach goal orientation t (23) = -0.81, p = .426. It showed that endorsed mastery-approach goal orientation remained stable after six months of treatment. The results of the study were linked with previously conducted research in the field of achievement goal orientation. Recommendations were made on the basis of findings of the study. The findings revealed that TARGET model is effective to endorse mastery approach goal orientation among students. It is, therefore, recommended that teachers should use masteryapproach goal endorsing instructional practices to make students mastery-approach goal oriented. Results proved that instructional practices prescribed in TARGET model also improved students'' achievement in the subject of mathematics. Results of the Board of Intermediate and Secondary Schools show that students are performing poorly in the subject of mathematics. It is therefore recommended to arrange workshops, seminars and teacher training programs to make teachers aware of mastery goal structure of instructional practices delineated in TARGET model. It will make students more mastery-approach goal oriented which will, ultimately, improve their performance in mathematics.