In Turkey, students are placed in a high school according to the scores they receive from a large-scale transition exam. Although the assessment procedures have shown changes over time, scores of this exam still play a vital role in students being accepted into a prestigious high school, which may also be an initial step for their prospective achievement at the higher education level. Therefore, this study aimed to analyze the student-, parent-, and school-related variables affecting eighth grade students' academic achievement on high school transition exams (TEOG) in state secondary schools in Eskisehir, Turkey, along with the relationships of these variables, by using hierarchical linear modeling (HLM). Study participants included 667 students and their parents as well as 211 school leaders and teachers. The results showed that schools located in high socioeconomic status neighborhoods received higher effectiveness scores. The first HLM analysis indicated that 37% of the variation in the TEOG scores resulted from schools. School effectiveness was responsible for 85% of variation in scores. In the second HLM analysis, it was found that school socioeconomic level created a 76% of variation in scores. Although cross interactions in both analyses were significant, the percentage of their explained variance was rather low. The findings of this study could be used to take reasonable steps to improve educational decisions and might give insights to students, parents, and educational leaders to increase students' academic achievement in the process of transition to high school.