The study aimed to measure the effectiveness of a training program based on constructivist theory in developing constructive teaching practices and reading comprehension skills for Arabic language teachers. It also aimed to explore the impact of developing their teaching practices on the development of reading comprehension skills for their students of grade 10 in Batinah South Governorate, Sultanate of Oman. The sample consisted of 40 male and female teachers who were randomly distributed with equal number in both experimental and control groups. To achieve the goals of the study, the researcher prepared a set of tools, namely: an observation card for constructive teaching practices, an observation card for reading comprehension, a reading comprehension test for students in the experimental and control groups of 400 students, and a measurement tool for teachers' attitudes toward constructive teaching. The study adopted Semi-experimental approach. The study included a list of principles of constructivism as well as a list of reading comprehension skills in five levels: direct, deductive, critical, gustatory, and creative. There is also a guide to describing constructive teaching practices, a guide to describing reading comprehension practices, and the training program. The training program was based on integrative principles of cognitive constructivism, social constructivism, and four teaching strategies and models emanating from them. These are: problem solving strategy, Jigsaw cooperative learning strategy, the seven-cycle learning model, and the generative learning model. The study concluded that: - There are statistically significant differences between the mean of the experimental and control groups in constructive teaching practices in post application in favor of the experimental group. - There is no statistically significant effect of the interaction between group type and gender variable in constructive teaching practices among Arabic language teachers. - There are differences in reading comprehension practices between males and females in favor of females. -There are differences in developing reading comprehension skills of grade 10 male and female students in favor of the female. In the light of the results, the study listed several recommendations including: holding training courses for Arabic language teachers to raise their level of knowledge of educational theories and their applications in classroom teaching practices. Moreover, it recommended developing teachers' guides by including constructive teaching strategies, and models of constructive activities that focuses on students-centered learning in the classroom and develops reading comprehension levels. The study also suggests making use of the two cards of constructive teaching and reading comprehension in educational supervision and making use of the reading comprehension test to train students to do similar skill tests.