In this study, the effects of students' attitude towards English, foreign language anxiety, exposure to English, school type (i.e. state or private), parents' English proficiency and education level on the students' English achievement in TEOG exam are investigated. To achieve this goal, a multiple indicators and multiple causes (MIMIC) model has been developed, and tested based on Stephen Krashen's language acquisition theory and the literature. According to the research results, attitudes towards English, school type, amount of English exposure, parents' education level and English proficiency have meaningful and positive effects on English proficiency, while language anxiety has a meaningful but negative effect on it. Moreover, it was found that the effects of parents' education level and English proficiency and the students' attitudes towards English on English proficiency are mediated by exposure to English. Therefore, Krashen's second language acquisition theory stating that those who have positive attitudes towards English will seek more comprehensible input and so will be more exposed to English and consequently will acquire English more is validated.