The outcomes of this research are manifold. I present the contributions in three parts, corresponding to the three key organizing ideas. First, it is observed that user context is key to characterizing communication between a pair of individuals. However interestingly, the probability of future communication seems to be i more sensitive to the context compared to the delay, which appears to be rather habitual. Further, it is observed that diffusion of social actions in a network can be indicative of future information cascades; that might be attributed to social influence or homophily depending on the nature of the social action. Second, it is also observed that different modes of social engagement lead to evolution of groups that have considerable predictive capability in characterizing external-world temporal occurrences, such as stock market dynamics as well as collective political sentiments. Sihem Amer-Yahia and Dr. Doree Duncan Seligmann during these three internships.The research I accomplished during these internships, enabled with the wonderful computing infrastructure and the rich availability of data, will remain very central to my academic accomplishment during the graduate school years. Additionally, encouraging discussions, fruitful guidance and generous help from Winter, Jake, Cong, Ronny, Ajita and Michael also helped me gather enthusiasm, have fun and remain on top of exciting research problems.