Drawing on fifth wave data from the Korean Education Longitudinal Study (KELS) 2013, this study examined the structural relationships between parental socioeconomic status, social networks, educational aspirations, knowledge of school information, and middle school students’ preparation for entry into high school using structural equation modeling (SEM). Our SEM results showed that both parental education level and household income had a positive effect on the parents' social networks, educational aspirations, and knowledge of school information. While parental education level exerted a significant effect on students’ preparation for entry into high school, household income had little effect on it. Parents' social networks and educational aspirations exerted a significant effect on knowledge of school information. Lastly, parents’ educational aspirations and knowledge of school information had a positive impact on students’ preparation for entry into high school. This study is expected to broaden the horizon of educational gap research by empirically exploring how parental socioeconomic status can affect their children's educational outcomes through differentiated social networks and school information.