Greenways provide much-needed natural corridors and environments in urban and suburban areas, along with recreational, transportation and nature education opportunities for urban residents. However, there is a tension between the natural environment and public use in urban areas. Local residents' concerns for safety through clear sightlines and the use of lighting along trails may compromise the ecological integrity and natural character of urban greenways, whereas natural corridors in the city are often considered as being potentially unsafe, and therefore essentially inaccessible to use by many residents, particularly women, children, aging people and those with disabilities. As a result, the planning and development of safe urban trails within natural greenways can be challenging and contentious. Prospect and refuge theory provides a theoretical framework for understanding the human ecological dimensions of environmental design. Within this framework, a growing body of environment-behavior research provides useful principles for planning and designing greenways that are both ‘green’ and safe. These principles include: visibility of others, visibility by others, choice and control, solitude without isolation, and environmental awareness and legibility. This paper outlines the ‘safe communities’ approach developed in the city of Toronto, Canada, and applies it to the planning and design of trails in urban greenway systems through a series of planning guidelines, with particular reference to the Greater Toronto Area experience. The paper concludes that only when public safety is paramount will the necessary community support be built which will allow the successful integration of natural greenways into the fabric of metropolitan areas.