This article approaches the concept of public interest in planning from the point of view of Patsy Healey’s collaborative planning theory on one hand and, on the other, from the perspective of Habermasian philosophy, one of the sources of inspiration for collaborative planning. In its original form, the theory of collaborative planning prioritized the ways in which local communities can communicatively define the interests they share and have an influence on the places they share under the current conditions of pluralism of ways of life. This article asks whether collaborative planning theory can also look beyond locally focused notions of the public interest and whether the theory is useful also for trans-scalar problem solving, for instance, in the multicultural metropolises where the different locally defined "public interests" often contradict with each other. This article compares Healey’s answers to this problem with ones that could be derived from Habermas’ philosophy. It argues that in order to look beyond the locally focused notions of the public interest, the theory of collaborative planning could benefit from revisiting Habermas’ concept of "generalizable interest" and especially Habermas’ positioning of this concept in his works published after The Theory of Communicative Action.