The study aimed at investigating the impacts of mobile-assisted instruction on improving Iranian female EFL learners' speaking skill and exploring their perceptions of the experience. Random sampling was applied to select 90 female students at the Zand Higher Education Institute in Shiraz, Iran. Their ages ranged from 18 to 24. They were randomly assigned to one control and two experimental groups. The control group was subjected to traditional instruction and the experimental ones were subjected to mobile-assisted instruction on their course-related contents through Voice Thread and Twitter as their out-of-class activities for three months. The needed data were collected using speaking papers of the Preliminary English Test and an interview. A paired samples t-test and one-way ANOVA were used to compare the performances of the participants in the speaking pre- and post-tests. Findings revealed mobile-assisted instruction played a prominent role in improving learners' speaking skill. The interview results showed the majority of the participants (71.25%) had positive attitudes toward mobile learning. This study provided experimental evidence that both Voice Thread and Twitter could be used as educational tools to help the students of English as a foreign language to improve their speaking skill.