In this thesis, I have argued that only when literacy is understood as a social practice and the repertoires of the students who use it considered, can a spirit of learner-centeredness be enacted in Singapore's schools. It argues that adolescents engage in multimodal textual repertoires, in and out of school, which comprise the collective assembly, production on the go, multitasking and fun. These findings lead to an important understanding that literacy practices may be best understood as a complex configuration of school and home practices which cannot be easily disaggregated into separable school and home practices. This thesis also suggests that literacy and learning are inseparable in social practice, regardless of the sites of their occurrences. Rather than framing school and outside school as two clearly-bounded domains of literacy practices, this thesis contends that the connection between them is captured by the relationship amongst literacy demands, practices and technology affordances. Although this thesis shows that adolescents emphasise the social affordances of digital media in their out-of-school literacy practices, it argues that their participation in these practices have enabled them to meet the demands of their school work and thus sheds light on their ways of learning, namely learning by doing and social learning. Contrary to the widely-cited view that multiliteracies are paramount in this digital age, this thesis highlights the tension in adolescents' identities in learning and suggests that traditional print-based literacy in language learning remains key to their social futures. Drawing on the theoretical underpinnings of New Literacy Studies, this thesis adopted an ethnographic perspective to study ten 14-year-old Chinese adolescents' literacy practices in Singapore. Data for this thesis were collected over a period of eight months from participant observations, with video-and-audio recordings, conducted in a school in Singapore, semi-structured and in-depth text-elicited group and individual interviews, the adolescents' research diaries, and their artefacts from school and out-of-school literacy practices.