The automobile commute makes an important contribution to carbon emissions but has proven stubbornly resistant to modal shift policy initiatives. In this paper we use theories of social practice to develop insights into why this stubbornness might exist, and what might help accelerate transitions to bus- and cycle-commuting. By analysing qualitative data about everyday mobility in two UK cities, we examine how the availability of the constituent elements of bus- and cycle-commuting practices is crucial for modal shift to occur, but they are often absent. We also draw attention to time-space contingencies that render recruitment to low-carbon commuting practices more or less likely, including how commuting is sequenced with other social practices and how the sites of these practices interact with the affordances, and spatial infrastructure, of bus- and cycle-commuting. These insights lead us to argue that choice and land use planning focussed policy initiatives designed to invoke modal shift need to coexist in integrated policy configurations with initiatives designed to reshape both mobility and non-mobility practices. This means addressing the structural barriers caused by the lack of availability of the elements that constitute bus- and cycle-commuting, and intervening in the timing and spatiality of a range of social practices so as to reduce the tendency for commutes to have spatial and temporal characteristics that militate against the use of bus and cycle modes.