The organisation of time at school has important implications for adolescents' development and achievement, and educators' management of out-of-school time. However, this has been a somewhat neglected research area. This paper comprises a scoping review of existing literature and secondary analysis of data on school time, in order to map out the territory, identify emerging time trends, and clarify the need for further research. It finds that UK school timetables and calendars are similar over 30 years despite considerable legal freedom to re-organise them. However, subtle shifts have occurred including (a) the National Curriculum reducing flexible off-curriculum teaching time, (b) decreasing lunchtime and no more afternoon break, (c) shorter school days and extended schooling, (d) more pastoral time, and (e) the increasing prevalence of 16-18 year olds in educational tracks instead of employment. Our review points to adult agendas and cultural reproduction as driving forces behind the development of school time, rather than consideration of adolescents' developmental needs. (Contains 3 notes, 4 tables, and 5 figures.)