The study investigated the determinants of English reading and mathematics achievement in 1,656 11.5-year-old students from 60 schools in a developing country, the Philippines. The main variables of interest were related to socioeconomic status, out-of-school time (OST), and school quality. The correlates of achievement were explored using two-level multilevel modeling, while controlling for students' prior ability, to properly attribute the variance at the student- and at the school-level. Findings indicated that while schools accounted for approximately 2.6-5.6% of the total conditional variance, they were important in the production of higher academic achievement. The presence of electricity in a school was associated with higher levels of achievement while more years of teacher experience at the school was negatively associated with academic achievement. In addition, OST variables (i.e., time spent doing homework, sleeping, watching television, playing, traveling) were also significantly associated with student outcomes. Supplemental analyses were also conducted using multilevel structural equation modeling. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]