More often than not in India, many informal settlements of urban poor (slums) are missing from city maps and various planning documents. The Society for Participatory Research in Asia, in its work with partner organizations for strengthening civil society voices on urban poverty, undertook a process of intervention. The communities in different slums were organized to take action to map their settlement. Community members were trained in the use of digital mapping tools. Through this action, communities were sensitized about their marginalization in the urban planning process and collectivized to take further action demanding their rights from municipal authorities. This paper outlines the process of training and collectivizing communities, the impact of the intervention, and the lessons learned.