The study investigates the effect of explicit contrastive analysis and translation activities on the incidental acquisition of single words and collocations. We compared three high school groups of learners of the same L1 and comparable L2 (English) proficiency. Each group represented one instructional condition: meaning focused instruction (MFI), non-contrastive form-focused instruction (FFI), and contrastive analysis and translation (CAT). The target items consisted of ten unfamiliar words and ten collocations in L2—English. The MFI group performed content-oriented tasks which did not require attention to the target items. The FFI group performed text-based vocabulary tasks which focused on the target items. The CAT group was assigned text-based translation tasks: from L2 into L1, and from L1 into L2. During the correction stage, the teacher provided a contrastive analysis of the target items and their L1 translation options. Time-on-task was kept constant in the three groups. After completing the tasks, the three groups were tested on the retention of the target items by two tests: active recall and passive recall. A week later, the participants received the same tests. The CAT (contrastive analysis and translation) group significantly outperformed the other two groups on all the tests. These superior results are discussed in light of the ‘noticing’ hypothesis, ‘pushed output’, ‘task-induced involvement load’, and the influence that L1 exerts on the acquisition of L2 vocabulary.