This book brings together linguistic, psycholinguistic and educational perspectives on the phenomenon of cognate vocabulary across languages. It presents a large-scale, long-term research project focusing on Polish-English cognates and their use by bilingual and multilingual learners/users of English. It discusses extensive qualitative and quantitative data to explain which factors affect a learner's awareness of cognates, how adult learners can benefit from raised awareness and whether cognate vocabulary can be used with younger learners as a motivational strategy. The work shows how cognate vocabulary can be examined from a range of methodological perspectives and provides considerable insights into crosslinguistic influences in language learning. While the focus of the studies is Polish-English cognates, the research will be of interest to anyone teaching learners of different language constellations, levels, ages and backgrounds.