Connectionist approaches to social networks often speak of flows of ideas, attitudes, and behaviors through ties as social influence and as peer influence in the specific case of flows among friends and acquaintanceships. Modeling social influence is no easy task. How do we determine where a particular idea came from in a network and who influenced whom? In establishing the presence of social influence, a researcher must theoretically and empirically address many potentially confounding factors and alternate explanations. In the previous chapter, we covered network approaches to generic flows at scale. In this chapter, we more thoroughly cover some of the thorny issues involved in tracing interpersonal influences and key modeling strategies in obtaining more detailed views of what flows and to whom.