This study aimed at investigating the effect of electronic dialogue journaling on Jordanian upper basic stage EFL students' writing performance. The study utilized a pretest-posttest control group experimental design. The subjects of the study consisted of fifty students enrolled in the Islamic Educational School during the first semester of the academic year 2007-2008. These subjects were randomly assigned to an experimental group and a control group. Both groups were pre-tested before conducting the experiment. During the experiment, the experimental group wrote dialogue journals to their instructor via email whereas the control group wrote on paper about the same topics at the same rate. The experiment lasted for four months. After the experiment, both groups were post-tested using the same test. The obtained data were analyzed using the t-test. The findings revealed that there was no significant difference in EFL writing performance between the two groups on the pre-test. However, the findings showed that there was a statistically significant difference in EFL writing performance on the post-test in favor of the experimental group. These findings suggest that electronic dialogue journaling is an effective method for developing EFL students' writing performance. Therefore, EFL teachers should incorporate it into their writing instruction and future researchers need to investigate its effect on EFL students' reading and speaking skills. Appended are: (1) El-Koumy's Scale for Marking EFL Students' Writing; and (2) Topic List. (Contains 2 tables.)