The HeatResilientCity project applied insights from natural sciences, engineering and the social sciences to develop heat adaptation measures, test their effectiveness and partially implement them in two structurally different real-world laboratories in Dresden-Gorbitz and Erfurt-Oststadt. The present article discusses interventions to plant street trees and to refurbish two different residential buildings. We describe and analyse aspects of the implementation process to identify key factors that enable or constrain adaptation action among different groups of actors. We find that adaptation measures that are objectively effective and supported by residents are most appropriate for implementation. Where residents evince scepticism about adaptation measures, information about their effectiveness and usefulness should be disseminated. Early and targeted involvement of relevant stake-holders, careful communication and the establishment of climate adaptation as a permanent interdepartmental task at municipal level can promote successful implementation of heat adaptation measures.