This paper analyzes barriers and opportunities for effective adaptation planning in cities. In particular, we focus on the preparation and adoption of adaptation strategies and action plans by urban planners. For this purpose, we develop a two-tier framework of variables influencing decision-making. The framework emphasizes interaction between different commonly discussed categories of barriers (or opportunities) and their sources. We argue that whether or not urban planners take action to foster adaptation to climate change depends on three first-tier variables: information, resources, and incentives. In addition, we point out that each of these variables may itself be a function of a set of underlying second-tier variables, including actor-specific characteristics of the decision-maker, the institutional environment, and the natural and socio-economic environment. Within this framework, we specify barriers and opportunities for effective adaptation planning as hampering or promoting characteristics of these first- and second-tier variables. We apply and test the framework within the context of four case studies carried out in Lima (Peru), Santiago (Chile), Berlin and Sangerhausen (both Germany). We present anecdotal evidence, which we have gained from expert interviews in the cities. Our results indicate that the relevant categories of barriers are mainly the same across developing and developed countries. What differs is their severity. Moreover, we confirm the importance of the institutional context, including barriers and opportunities associated mainstreaming adaptation, multi-level governance and participation. Finally, our analysis reveals barriers that are specific for local or urban adaptation action, such as the strong dependency on the national regulatory framework.