This study was to explore how teachers participated in the community of practice and to investigate teachers’ professional development in reading comprehension instruction. Social constructivism and the concept of community of practice were used in the study. In this study, teachers were invited to participate in the community, and share their experience on reading comprehension instruction. Besides the processes of reading instruction, the contents of discussion in the community included teachers’ lesson plans of reading instruction as well. The participants of the community were six teachers and three researchers. Qualitative research approach was used in the study. The major findings were as follows: (1) Compare to teach students using the lesson plans done by the researchers, teachers know better how and why to do the reading comprehension instruction after they designed the lesson plans themselves. (2) Teachers relearned the meaning of reading comprehension and the instruction methods. Moreover, they gained the sensitivity to the texts before reading comprehension instruction. (3) Although the ways of instruction changes were stressful, teachers discovered the change in students which made them more confident in reading comprehension instruction. (4) When teachers were able to reflect on the interactions and sharing experience among teachers in the community, they better understood the instruction strategies. (5) The community is a support system for teachers which allowed them to explore the unknown. The results of the study showed that teachers can benefit from the community of practice. Teachers discussed their practices in the community, shared their experience, and gained new knowledge of practice in the community.