This study aimed to explore the relationship between language acquisition and grade four senior high school (G4SHS) students’ achievement in English as a foreign language (EFL). To this end the 41-item English Language Acquisition Scale (ELAS) designed by Khodadady and Younesi (2017) was administered to 518 G4SHS students. Also to find the probable relationship between ELAS, its latent variables and participant achievement in EFL classes in EFL classes 126 participants were randomly selected out of population to answer schema-based cloze multiple choice items test ( S- test) designed by Khodadady and Ghergloo ( 2013). To know which of the G4SHS students who took the ELAS took the S-Test as well the researcher was matched the codes of the ELAS S-test and ELTAS carefully. The results showed that the ELAS consists of five factors, i.e., Qualified, grammatization, Humanistic, Engagement and Orientation. Also the ELAS and its underlying factors show significant relationships with English achievement scores. The results of the study are discussed .
