This paper presents a comparison of the structure, function, and value of street and park tree populations in two California cities. Trees provided net annual benefits valued at $2.2 million in Modesto and $805,732 in Santa Monica. Benefit-cost ratios were 1.85:1 and 1.52:1 in Modesto and Santa Monica, respectively. Residents received $1.85 and $1.52 in annual benefits for every $1 invested in management. Aesthetic and other benefits accounted for 50% to 80% of total annual benefits, while expenditures for pruning accounted for about 50% of total annual costs. Although these results were similar, benefits and costs were distributed quite differently in each city. Variations in tree sizes and growth rates, foliation characteristics, prices, residential property values, and climate were chiefly responsible for different benefits and costs calculated on a per tree basis.