Since the adoption of Agenda 21 at the UN Conference in Rio de Janeiro in 1992, cities have been assumed to play a central role in achieving global sustainability goals. Numerous cities around the world are fulfilling this task by using innovative and comprehensive policy tools. A considerable variety in the usage of policy instruments can be observed among German cities. While some cities show a high commitment to sustainability, others do not even address the topic at all. In Germany, sustainability policy regularly falls within the scope of voluntary municipal tasks. Legally binding requirements from higher levels hardly exist. Moreover, sustainability policies are characterised by several properties that should actually make them unattractive for cities to be worked on. Additionally, sustainability policies have to be driven forward by cities under rather unfavourable conditions like increasing financial constraints. Why should cities in Germany nevertheless commit to sustainability in a comprehensive manner? This article addresses this question with the help of cross-sectional regression analyses of the sustainability policies of 189 cities in 2021. This is the first quantitative analysis to examine the influence of various socio-economic, institutional and political factors, which are discussed to have explanatory power in the international research literature on urban sustainability policy and in the research literature on local policy-making in Germany. To measure sustainability commitment, a new dataset was created by using internet sources, in which the sustainability policy instruments of 189 large and medium-sized cities were systematically recorded, coded and finally aggregated into an index.
