Portland's trees soften and beautify the built environment, improving neighborhood safety and livability and providing vital ecosystem services such as air purification, temperature mitigation, and stormwater interception. In a study released in October 2007, Portland Parks Urban Forestry evaluated and quantified the benefits provided by Portland's urban forest canopy, focusing on publicly owned street and park trees. Field data were analyzed along with hourly meteorological data, resource management costs, and the rates of accrual of the environmental and aesthetic benefits trees provide based on annual growth modeling. Satellite image interpretation determined citywide canopy cover for public and private property, a hypothetical future-canopy target, and the environmental benefits of both. Results reveal that Portland's urban forest canopy is a complex, multi-species, multi-aged resource valued at roughly $5 billion that produces over $52 million in environmental and aesthetic benefits annually. Roughly 1.5 million trees grow on publicly owned property, comprising just under half of the urban forest canopy, costing the city and private property owners over $6.5 million annually to maintain, and returning $3.80 in benefits for each dollar invested in their care and maintenance. This talk will focus on the methods used to determine the infrastructure value of the trees themselves as well as the environmental and aesthetic benefits the trees provide.