This study aimed to investigate the relationship between intelligence and learning English ingeneral, and learning grammar and reading comprehension in particular. Participants wereteenage Iranian learners from Kerman high schools in second grade. The tests wereadministered at the end of the year to two mixed classes of 60 learners whose ages ranged from15 to 19. Standardized tests were employed to assess learners' performance in readingcomprehension, grammar and intelligence (both verbal and nonverbal). The correlation betweenthe two variables was determined through Pearson Product-Moment Correlation Coefficient.Results of the investigation showed that unlike first language acquisition, there was a positivecorrelation between verbal and nonverbal intelligence and learners' English languagedevelopment. Data analysis showed that the relationship between intelligence scores and thoseof comprehension and grammar scores was significant across all the groups. The results of thisresearch prove that intelligence is one of the important factors in acquisition of English as aforeign language, but it is not the only factor.