Trees make our cities more attractive and provide many ecosystem services, including air quality improvement, energy conservation, stormwater interception, and atmospheric carbon dioxide reduction. These benefits must be weighed against the costs of maintaining trees, including planting, pruning, irrigation, administration, pest control, liability, cleanup, and removal. We present benefits and costs for representative small, medium, and large deciduous trees and coniferous trees in the Northern California Coast region derived from models based on research carried out in Berkeley, California. Average annual net benefits (benefits minus costs) increase with mature tree size and differ based on location: $29 (public) to $41 (yard) for a small tree, $42 (public) to $60 (yard) for a medium tree, $101 (public) to $122 (yard) for a large tree, $142 (public) to $146 (yard) for a large conifer. Two hypothetical examples of planting projects are described to illustrate how the data in this guide can be adapted to local uses, and guidelines for maximizing benefits and reducing costs are given.