In social interaction systems, the formation and testing of theories is significantly difficult because social interaction systems cannot be easily manipulated and controlled. It is also not possible to reproduce large-scale systems in a lab setting or in a short fixed time duration. Detecting short-term non-recurrent interactions between individuals is very different from studying an individual’s long term social group(s). However, over the last decade the rate of digital data availability using smartphones and wearables has increased consistently at a high pace which allows social scientists gain a comprehensive understanding of how groups form and evolve over time using recurrent in-person interaction networks. In this paper, we design a long term data-driven study on a finite student population of a residential university campus. Our aim is to study a student’s recurrent in-person interactions, or long-term social groups, between the time that one enters into a cohort, e.g. Class of 2022, and until that cohort graduates. In this sensor-data driven study using state-of-the-art interaction-detection algorithms, we monitor parameters such as social group size, formation-time and longevity. We also conduct a retrospective cohort analysis of self-reported social group parameters, e.g. social group size, time spent with each group type and associated satisfaction. Preliminary results from the same make an extremely strong case for a longitudinal study, especially indicated by the evolution of one’s social circles over a long period of time. © 2019 Copyright held by the owner/author(s). Publication rights licensed to ACM.