Indonesia has committed to accomplish "cities without slum" target in 2019 through the national program of Action Planning for Preventing and Improving the Quality of Urban Slum Settlements (RP2KPKP) launched in 2015. Nanga Bulik town in Kabupaten (Regency) Lamandau of Central Kalimantan Province is among those included in the program; the RP2KPKP of which has been completed in 2016. This paper focuses on how participatory approach has been applied in the planning process. The planning has employed mostly qualitative approach with documents study, field observation, and Focus Group Discussions (FGDs) involving all stakeholders, complemented with quantitative one especially in the aspects of urban and architectural design. The findings have suggested that the community participation in Nanga Bulik case has gone beyond the requirement commanded by the Indonesian laws on development planning and spatial management to ensure the target achievement in 2019. It is crucial because a higher level of the plan implementability would ensure more sustainability of the slum improvement. Essential lessons can be learned from this real participatory planning, which could be the beginning of the third generation of planning in Indonesia.