Vocabulary research provides valuable information on the construct of word knowledge (WK), and suggests ways to develop language learners' lexicon, arguably, the backbone of communication. The present study explores EFL students' vocabulary learning behavior; more specifically, the aspects of WK components they intentionally focus on when learning new words. Data was collected from 536 undergraduate students in an EFL context. Our findings revealed that EFL students' vocabulary size was roughly 5,000 word families, considerably less than the number advocated for academic studies. Regarding the various aspects of WK, the top three components that the participants with larger vocabulary sizes primarily focus on were a word's meaning in L2, spelling, and pronunciation, whereas for those students with a smaller vocabulary size, the top three choices were meaning in L1, spelling and meaning in L2. This intentional focus on separate aspects of WK, especially the meaning-form link in L2, might instigate further progress for the former group, and the lack thereof may inhibit learning opportunities for the latter. Exploration of the processes of vocabulary learning will guide teaching practice, and materials design. It may also call for adjustments in curricula as our understanding of vocabulary acquisition processes evolves.