A number of methods are being undertaken in New Zealand to achieve sustainable land transport outcomes. Lower urban speeds (less than 50 km/h) are increasingly being used to improve safety, but may also contribute to other sustainable land transport outcomes. This research includes: a literature review, case studies, a survey of industry professionals and comparative analysis, to consider the potential effectiveness and efficiency of reducing urban speeds1 to achieve sustainable land transport outcomes. There is reasonable consistency between the findings of the survey, case studies and literature review. The key areas of difference relate to the survey responses potentially under-estimating political and public support for reducing speeds. The responses also over-estimate the current contribution of industry knowledge, and the adverse effects of travel times, vehicle emissions, and fuel usage. In respect to efficiency, reducing urban speeds can be successfully implemented in New Zealand, time and cost requirements are achievable, and legislation is permissive, but additional guidance and industry knowledge is required. Political and public opinions are difficult to determine but there is nothing to suggest that there is widespread opposition to reducing urban speeds, particularly in residential, high pedestrian and business areas. In respect to effectiveness, reducing urban speeds can contribute to improving: safety, public health, accessibility, integrated urban form, environmental sustainability2 and economic development. The impact of increased travel times on functional transport networks is likely to result in some adverse effects, but these are not likely to be significant. Compared to the provision of walking and cycling infrastructure, from the information available, reducing urban speeds is considered to be at least as effective at achieving sustainable land transport outcomes. Reducing urban speeds could also be as efficient, as provision of walking and cycling infrastructure, with more consistent political support, more guidance on the use of legislation, and once the level of industry knowledge improves.