This study examined reading motivation in Hong Kong secondary school students, taking account of school-related factors of medium of instruction, teacher support and peer support and demographic factors of gender, grade and socio-economic status. Specifically, the research questions were: (1) How are the school factors of medium of instruction, teacher support and peer support related to reading motivation in Chinese (first language; L1) and reading motivation in English (second language; L2)? (2) How are the demographic factors of socio-economic status, gender and grade related to reading motivation in Chinese and English? and (3) Are there differential patterns of prediction of school factors and demographic factors for Chinese and English reading motivation? The SRQ-Reading Motivation Questionnaire, designed to measure reading motivation as conceptualized by Self-Determination Theory (SDT), was adopted. Nine hundred and forty-one secondary school students participated in this study, from the grade levels of secondary one, four and six in seven secondary schools in Hong Kong. Confirmatory factor analysis indicated that their reading motivation was comprised of two factors, Autonomous Chinese Reading Motivation (ACRM), Autonomous English Reading Motivation (AERM), Controlled Chinese Reading Motivation (CCRM) and Controlled English Reading Motivation (CERM). To address the three research questions, structural equation modeling was used to investigate the relationships among the variables examined in the present study. The findings showed that Teacher Support significantly predicted all reading motivation outcomes. A higher level of teacher support was associated with higher levels of autonomous and controlled reading motivation in the two languages. Peer Support was also a significant predictor of all reading motivation outcomes. Surprisingly, peer support had a negative relationship with controlled reading motivation in Chinese and in English but a positive relationship