The thesis is a trans-disciplinary work on participatory e-planning. It highlights the importance of taking participation in the design of digital technology into consideration when exploring the way participatory e-planning is currently evolving and how it might be shaped in the near future. The focus on the design of digital technology is balanced with sensitivity to urban planning. The outcome is a work that introduces a mixed conceptual vocabulary and provides outcomes of relevance to several different fields operating at the intersection of digital technology, urban planning, and participation. The thesis aims in particular to reduce the current gap between the fields of urban informatics and e-planning.