Abstract The present study investigated the impact of using mobile learning on Grade 11 students' vocabulary learning, retention and their attitudes. The study is a quasi-experimental study and the population of this study consisted of 1671 Grade 11 female students in Post Basic Schools in Dhofar in the academic year 2014-2015. Two schools were selected: A Saadah Post Basic School and Al Nahda Post Basic School. Two classes comprised the sample of the study, one class from each school. The two classes were randomly assigned. The experimental class included 22 students and the control group had 24 students. A vocabulary test (pre-test, immediate post-test, delayed post-test) and an attitude questionnaire were used to collect data needed to answer the research questions. Yay. The major findings of this study are as follows: 1. There was no significant difference in vocabulary achievement between students who learned vocabulary through mobile phones and students who learned vocabulary in the conventional way. 2. There was a significant difference in vocabulary retention between students who learned vocabulary through mobile phones and students who learned vocabulary in the conventional way in favor of the experimental group. 3. The experimental group generally had a positive attitude towards using mobile phones in learning. In the light of these findings, recommendations and suggestions for further research were offered