The present study employed a mixed methods quasi-experimental design to investigate the effectiveness of applying motivational strategies and mental imagery (i.e. visionary techniques) to facilitate second language (L2) vocabulary learning. Four treatment sessions were integrated into a six-week language course offered to 150 intermediate students in nine classes of English as a foreign language (EFL), which were divided into three groups: motivational group, visionary group and control group. The target language items involved 56 formulaic sequences, and the outcome was assessed by a multiple-choice vocabulary test. The quantitative results were accompanied by qualitative data, aimed at gaining a deeper understanding of the test results. The findings revealed that both motivational strategies and visionary techniques proved effective in increasing the students' ability to recognize the form of the target sequences, and that the visionary condition was superior to the use of motivational strategies. The benefits of the deeper engagement level associated with mental imagery were corroborated by a delayed posttest. The article concludes with a theoretical discussion of the benefits of visualisation in vocabulary acquisition.