ABSTRACT: BACKGROUND:Living in urban or rural environments may influence children's levels of physical activity and sedentary behaviours. We know little about variations in device-measured physical activity and sedentary levels of urban and rural children using nationally representative samples, or if these differences are moderated by socioeconomic factors or seasonal variation. Moreover, little is known about the influence of 'walkability' in the UK context. A greater understanding of these can better inform intervention strategies or policy initiatives at the population level. METHODS:Country-wide cross-sectional study in Scotland in which 774 children (427 girls, 357 boys), aged 10/11?years, wore an accelerometer on one occasion for at least four weekdays and one weekend day. Mean total physical activity, time spent in sedentary, light, and moderate-to-vigorous physical activity (MVPA), per day were extracted for weekdays, weekend days, and all days combined. Regression analyses explored associations between physical activity outcomes, urban/rural residence, and a modified walkability index (dwelling density and intersection density); with interactions fitted for household equivalised income and season of data collection. Sensitivity analyses assessed variation in findings by socioeconomic factors and urbanicity. RESULTS:Rural children spent an average of 14?min less sedentary (95% CI of difference: 2.23, 26.32) and 13?min more in light intensity activity (95% CI of difference, 2.81, 24.09) per day than those from urban settlements. No urban-rural differences were found for time spent in MVPA or in total levels of activity. Our walkability index was not associated with any outcome measure. We found no interactions with household equivalised income, but there were urban/rural differences in seasonal variation; urban children engaged in higher levels of MVPA in the spring months (difference: 10 mins, p?=?0.06, n.s) and significantly lower levels in winter (difference: 8.7 mins, p?=?0.036). CONCLUSIONS:Extrapolated across one-year, rural children would accumulate approximately 79?h (or just over 3?days) less sedentary time than urban children, replacing this for light intensity activity. With both outcomes having known implications for health, this finding is particularly important. Future work should prioritise exploring the patterns and context in which these differences occur to allow for more targeted intervention/policy strategies.