Hong Kong attained the top place in the Progress in International Reading Literacy Study (PIRLS) 2011, an international study of reading achievement, which arouses keen interest in understanding the reasons behind this remarkable achievement. Although factors associated with reading achievement in English have been widely studied, similar studies using Chinese as a different language system are limited. The present study proposes and tests a hypothetical model that attempts to explain the variance of reading achievement of Hong Kong pupils in the PIRLS 2011 study, focusing on parental and student factors. Data of 3,875 fourth graders from 132 primary schools and their parents or caregivers (n = 3,682) are involved in the analysis. Structural equation modeling supports the hypothesized model as tenable explaining 34% of the variance of reading achievement. Parental background acts as the fundamental factor that exerts an indirect effect on reading motivation, reading self-efficacy, and reading achievement of students via books at home and early reading abilities. Reading motivation and reading self-efficacy are found to be significant in influencing reading achievement. Implications for educational practices and future research are discussed.