The article presents psychological and pedagogical peculiarities of preparation and organization of procedures for involving adolescents in participatory design of urban development processes. Using the example of the 3day competence test "Moscow Competence Olympiad", the possibility to ensure the quality of co-design through short-term intensive project-analytical sessions is investigated. Special attention is paid to the specifics of setting an educational task for the participants of the event, which performs the function of adapting complex material, providing higher accessibility to the problems of urban development for adolescents. The method of the research was an ascertaining experiment, which, from 2019 to 2021, involved more than 500 students of 8-11 forms of schools from 12 districts of Moscow, 14-18 years old, who took part in the Moscow Competency Olympiad in Management. The research showed that it is possible to effectively involve adolescents in the process of co-design of urban development processes that require high level of theoretical equipment and analytical abilities from decision-making subjects. The key means of involvement can be an educational task which adapts the problematic of urban development in the format of a search and analytical task which requires collective-distributed activity in the group work format.