The aim of this contribution to the PROSE Project is to analyse the characteristics of an opportunistic social environment and defining the notion of opportunistically oriented people. o study these opportunistic behavior, we conducted two studies. The first is intitled “Preliminary notes: serendipity, opportunities, curiosity”. It shows how people develop opportunistic strategies in the context of social networking to increase their networks of relationships and the frequency of their exchanges. The second is intitled “Study on the uses of Facebook in situations of mobility” and it is structured in two parts. This research is central to our contribution. It discribes and analyzes uses of digital social networks developed in mobility using smartphones, and more specifically uses of Facebook Places to share its geographical location using geolocation. The aim is also to understand the opportunistic strategies developed by users to increase their connection to digital social networks. To achieve this goal, we develop a novel research methodology in the field of social sciences and humanities based on the recording of the utilisations of smartphones. These videos allow us to offer a very detailed analysis of the uses of social networking applications. This research shows how users develop opportunistic behaviors based on the “pragmatic texture of mobile interfaces”.