This paper describes the effects of Seating for Socializing (SOS), a place-making project designed to revitalize open public spaces in Hong Kong which suffer from a lack of urban life. The study was conducted by combining quantitative and qualitative methods in order to understand the impact of this temporary urban design intervention in different spatial contexts. The results suggest that the use of bottom-up approaches and tactical design actions can be a valuable tool for promoting new social relations among the citizens as well as rethinking existing weaknesses in the conditions of the city’s public spaces.