A growing number of companies are faced with the challenge of implementing sustainable design. Although theory and methods are available, practice shows that the implementation process of sustainable design is not straightforward. In this paper, different cases are described based on an empirical study of Flemish and Dutch firms that are implementing sustainable design. The emphasis is put on the exploration of two human factors and their relation to the implementation process: resistance against sustainability and internal communication on sustainable design. Concerning the implementation process, the results indicate that factors of resistance appear to vary in nature and content throughout the implementation process and within different departments. Lastly, three communication types are suggested that ask for consideration to involve, support and inform employees in order to progress into the direction of sustainable products. The results of the exploratory study led to the formulation of four propositions.