The temperatures and the amounts of air pollution experienced in urban environments are typically larger than in surrounding rural environments. Urban air pollution is associated with increased cardiovascular and respiratory diseases, some cancers, and increased temperatures with discomfort and in the vulnerable and elderly increased mortality. Managing urban air quality by reducing pollution exposure and maintaining equitable urban temperatures are priorities towards enhancing the health and well-being of the urban population. This chapter explores how, and to what extent, urban vegetation can influence the amounts of air pollutants and regulate urban air temperature. Urban vegetation generally has a positive influence, and under some circumstances, the capacity to make substantial gains in urban air quality and temperature regulation. Different species and forms of urban vegetation had different influences, as did the location of planting, but under some circumstances vegetation could negatively influence air-pollution and temperature. Approaches to maximise the benefits from planting urban vegetation are presented and it is acknowledged that more research is needed in order to optimise these benefits.