Urban green may be seen as an important constituent of urban quality of life and the quality of urban green spaces as a key factor in making cities attractive and viable places to live in. The aim of this contribution is to investigate urban green spaces as a set of specific urban public environmental goods on the basis of a systematic assessment approach. The main question addressed is: 'Which types of evaluation approaches are appropriate for urban green spaces?' Several functions of urban green spaces such as utilization, production, employment, education, regulation, and preservation form the basis for the determination of dimensions, criteria and indicators that are relevant for the assessment. The classification of urban green values offers a comprehensive evaluation framework for urban green spaces from several perspectives at a conceptual level. Urban green spaces can be used by organizations that encourage the human spirit to value the challenge of self-competence, preferences for teamwork or alone.