This study investigated the effect of a multimedia tool on vocabulary achievement, retention and attitudes of young Omani EFL learners. It adopted a mixed methods design. The participants were 112 grade three young learners in cycle one of Basic Education schools aged 8-9-year-old studying English for Me (EFM) syllabus in two government schools in Batinah North governorate in the second semester of the academic year 2013-2014. The sample was selected using multiple-stage sampling. In the first school, two intact classes performed as the experimental group, and they were taught 39 content vocabulary items with the aid of the multimedia tool designed by the researcher. In the second school, two intact classes performed as the control group and were taught the same words aided with conventional word cards and flash cards throughout the 7-week period. Quantitative data were collected through a vocabulary achievement test developed on the basis of EFM learning objectives and was administered as a pretest, immediate posttest and delayed posttest. Other quantitative data were collected through a Learner Attitudes Questionnaire (LAQ) with a sample of 30 learners from the experimental group. To support the results of the study, qualitative data were collected. These included a focus group discussion with 16 grade three learners from the experimental group other than those who responded to the questionnaire. In addition, classroom observations to the experimental and control groups were conducted, and a written reflection from the teacher of the experimental group was obtained. The main results of the study were: 1- The results of the vocabulary immediate posttest and delayed posttest showed statistically significant differences at 0.05 level in vocabulary achievement and retention between the groups in favour of the experimental group. The results of the vocabulary delayed posttest showed no statistically significant differences at 0.05 level in vacabulary retention between males and females in both groups or betweenmales and females in the experimental group. 3. The experimental group-learners' attitudes towards multimedia were positive. 4- The focus group discussion highlighted cognitive, linguistic, affective and psychomotor benefits of the multimedia tool. 5- The classroom observations collected linguistic and non-linguistic data that revealed effective vocabulary instruction in favour of the experimental group. 6- The teacher's reflection outlined-teaching and learning benefits that improved her professional skills and her learners' vocabulary achievement and motivation. Drawing on these results, one could conclude that teachers of young learners may be encouraged to integrate multimedia tools in vocabulary instruction: The results also recommended initiating multimedia library to support cycle one English language syllabus, and conducting longitudinal studies on the effect of multimedia on young learners' language skill.