The urban sprawl process takes more places in the world by leaving gaps in the core of cities these days when some industrial areas have been abandoned or moved into greenfields of city periphery. A recent research has shown that most of the conversion of brownfields has done by participation process in Europe. Therefore, this movement does not have a strong basement in the post-soviet union countries, and it is becoming more fragmented and decentralized tool in the planning system where planners’ opinion still dominates. The paper analyzes the public policy in the planning system and uses the design proposal base by people’s opinions. The diploma thesis deals with how with the aid of the public participation process the development of the revitalization of brownfield projects in Vilnius can be influenced/changed. Moreover, planners started using the public opinion and participatory process in the last decade of the country existence. However, still most of the designs are made by them and still keep their strong position in the planning in Lithuania. The old school professionals are influenced by the socialistic urban developing system which has been impacted from the central government and giving all power to the planners and administration of the city. In Vilnius administrative territory, there are several regenerations and conversion projects going on. The study was focused on Markučiai and Paplauja industrial area conversion in Vilnius. The study area is “Park of Architecture” project territory, which is the biggest conversion project in Lithuanian at this moment. Inspired by the works of theorists and architects Lucien Kroll and Christopher Alexander on the participation process, they were chosen as the main guide for thesis. Therefore, the study territory is part/next to the main Vilnius city core – the old town which is a sensitive area for inhabitants of the city and country. The theoretical part is a review of the participation process and the potential of its application/use. The paper uses two analysises to get the best result for the design part. The Stakeholder analysis and case study approach are followed by interviewing the people related with the project area, looking through official “Park of Architecture” and Vilnius city developing documents, mapping and visit area. The paper indicates that the planners and public opinion are turning in a direction which is more flexible to interlocutor position and observation. However, the dominant opinion from both parts is to develop the area as part of the old town and find the connection with the natural environment. In the area, the functions have to have mixed use and to be available for the residents and visitors of the territory, as well as to the public areas, especially the quay on Vilnia river. After investigation, observation and analysis of the study area, gathered information showed that a territory between Markučiai and Paplauja has problems which are fixable and by emphasizing the opportunities and using the stakeholders’ opinions, the territory has a possibility of ecological and sustainable development. The study paper is finished with the design proposal which transforms the study area as part of the old town and the city, and makes it attractive for investment, living and working. Maybe this thesis will help other conversion and regeneration projects in Vilnius and other cities to avoid mistakes as well as will inspire to work more often with stakeholders in participatory processes.