The study aimed to design a program based on an e-community context to develop adult EFL learners' critical thinking. The study started with a review of the literature and previous studies related to critical thinking, its components, and e-communities where the study took place. The researcher designed the study instruments, including a pre-post critical thinking test, and a rubric. The researcher designed the proposed program for developing adult EFL learners' critical thinking. A group of voluntary adult Egyptian EFL learners (n=20) participated in the study. They studied eight online-based sessions, including the pre-post tests. Learners' scores on the pre and post-tests were statistically analyzed using the t-test, and the effect size. Besides, a qualitative analysis of the students' performance and satisfaction was conducted. Both quantitative and qualitative analyses revealed that the proposed program based on an e-community context was effective in developing adults' EFL critical thinking.