The study examined whether false-cognates, overlapping in form but not meaning across languages, are easier to learn due to form overlap, or more difficult to learn due to meaning competition, compared to unambiguous control and cognate words. Fifty-four native Hebrew speakers learned 14 cognates, 14 false-cognates, and 28 control Arabic words in one session. Cognates were learned better than control items. There was no overall difference in learning false-cognates relative to controls, but individuals with higher phonological short-term memory, or with lower L1 verbal fluency, did exhibit a false-cognate learning-advantage. For these individuals, form overlap was more influential than meaning competition. Lexical decisions to Hebrew words following Arabic learning were slower for false-cognates than controls, indicative of backward influences. The findings reveal the influence of prior knowledge on learning and processing, and highlight the importance of jointly considering item-based and learner-based characteristics during the initial stages of vocabulary learning.