The aim of this study was to investigate how the contextual vocabulary exploration processes of English as a Foreign Language learners can be facilitated in a mobile-supported situated learning environment. A Science and Technology Museum populated with interactive science experiments was chosen as the situated learning context. A mobile application was designed to support learners in completing the authentic tasks and facilitate learners in contextual vocabulary learning. During a 5-week period, 25 university students completed authentic tasks in the situated learning environment. An embedded mixed design, embedding a quantitative phase within a qualitative phase, was employed. The quantitative phase consisted of a pretest-posttest design and system logs, while the qualitative phase consisted of retrospective reviews and observation. The results indicated that contextual vocabulary learning can be supported and enhanced with mobile technologies by considering some factors, including contextual clues, word frequency, authenticity of the tasks, learners' domain knowledge, interest, and focus.