Public participation is the cornerstone of democratic urban planning. In this chapter, we approach public participation and collaboration among lay people and experts comprehensively. We approach the planning process as a flow of communicative actions where the knowledge needs and modes of working go hand in hand, sometimes opening up the process to large-scale participation and other times closing down the process to an intensive collaboration among smaller groups. We critically analyse public participation in the Helsinki master planning process using Staffans et al.’s 2019 model, which distinguishes four different modes of communicative actions in public participation. We especially focus on the study of how various communicative actions and digital tools can help address the existing challenges in public participation. Through a critical analysis and reflection upon a real-life planning case study using various tools and collaboration arenas, we examine the ability of digital participation tools to enhance communication in the various phases of urban planning processes. The results indicate that a more effective process design in arranging communicative actions with people is required.