The present study examined whether an improvement in English as a second language causes an improvement among poor readers in Hebrew as the first language. This assumption is named in the present study "The Cognitive-Retroactive Transfer (CRT) hypothesis of linguistic skills". The participants were 20 sixth-grade poor readers from Israeli elementary schools, with Hebrew as their first language, and who learn English as their second language. All the students in the program participated in small group instruction sessions that emphasized linguistic and meta-linguistic skills in the second language (English). The program, which was administered over a 5-month period, involved approximately 40 hours of contact with a trained instructor. The participants were administered various tests which measured their basic linguistic skills in English as well as in Hebrew. The tests were as follows: phonological awareness, phonological processing, word identification, reading fluency, reading comprehension, morphological awareness, syntactic awareness, orthographic knowledge and spelling. The tests in both languages were given to the participants before and after the intervention program. The test results indicated significant differences both in English and in Hebrew before and after the intervention program for all linguistic skills (except orthographic knowledge). The findings provide scientific support for the Cognitive-Retroactive Transfer (CRT) hypothesis, which means that an improvement in linguistic and meta-linguistic skills in a second language will be expected to give rise to a similar improvement in the first language as well. The results are discussed in light of the findings in the literature as well as suggestions for future research.