This chapter describes and illustrates the concept of temporary appropriation (TA) in relation to the informal use of the public space. To do so, it uses an assemblage thinking approach, describing the relationship between streetscape design and temporary appropriation. It offers a comparative assessment of three different cities across different continents. Algiers, Auckland and Mexico City, three cities with different cultural and historical backgrounds in terms of planning, design and urban behaviour. The instrumental case studies provide key indicators for the understanding of the relationship between the diversity of TA and the streetscape design in central areas of cities. In the present study TA is conceptualised as an assemblage of activities, as well as a social sustainability indicator strongly related to the design of the built-environment. The novel research findings include a new methodology for assessing cross-cultural environments, using mixed research methods that combine streetscape design analysis with TA mapping through participatory observation. The results illustrate striking differences between cities. The study findings show that TA diversity, intended as an indicator of inclusiveness, is more affected by cultural context rather than high-quality design. It also advances our understanding of environment and behaviour studies by using an assemblage thinking approach.