the ability to speak two languages in the world is a remarkable achievement. there is a good reason to believe that bilingualism is the norm for the majority of people in the world because 70% of the earth’s population are supposed to be bilingual or multilingual. various investigations have shown that the native language impacts foreign word recognition, and this influence is adapted by the dexterity in the non-native language. words being alike in two or more languages are called true cognates. false cognates are pair of words with similar form and pronunciation but different meanings in two languages. the present study explored the awareness and attitudes of iranian efl learner and teacher participants towards true and false cognates. it also investigated instructional value of teaching true and false cognate words. the participants were 385 learners and teachers. the learners with a mean age of 29 were studying at three educational levels at islamic azad university of zanjan, iran, and the teachers were teaching english at private language schools in zanjan, iran. each educational level was considered as one category, and the total sample was calculated using cochran formula. to study the effects of educational level on the awareness and attitude of the learners, analysis of variance (anova) was utilized. the results of duncan test showed that there was no significant difference among the participants with three distinct educational levels regarding their awareness of cognates. however, there was a significant difference between the level of awareness of teacher group and the associate, bachelor and master groups in the case of true cognate words. as for false cognate words, this study found no significant difference in the rate of cognate awareness among four groups. as for attitude, it was found that true cognates are effective in learning new words, and false cognates are effective in making students commit mistakes. the results of anova showed that there were no significant differences among university students’ attitudes to cognate use. cognates were also taught to a group of ba students (n=90) divided into one control and one case group. after administering one-week awareness-raising activities on true and false cognate words to the case group, the participants in both groups were examined with their recalling of 30 true cognates and 30 false cognates through an independent t-test. the findings demonstrated that there was a significant difference between the two groups in their recalling ability. the findings of this investigation conjointly verify the expectations that cognate-based instruction could facilitate second language acquisition. the results suggest that the participants do not recognize cognates as easily as presumed by textbook publishers and other authors. this study also found that that positive transfer, in the case of true cognates, is applicable for second language learning and teaching.