Social factors have long been associated with individual variation in behavior, physiology, health, and survival in non-human animals and humans. Yet, establishing the causality of these social influences and the mechanisms by which they act has been challenging. Among wild animals, uncontrollable genetic and environmental variation frustrates causal conclusions. And lab environments are unable to replicate the dynamic, complex social behaviors of natural populations. In this talk, I describe a solution to this problem: studying genetically identical laboratory mice in controlled, naturalistic outdoor enclosures. In such environments, mice navigate complex, dynamic physical and social environments that better match those that they evolved to exploit. I will describe work in which I have established the impact of social competition and luck on the development of individuality, causal links between social status and behavior and fitness outcomes in males, and the causal impact of social status on molecular physiology. The combination of behavioral ecological methods and theory with the scientific power of the lab mouse has opened up exciting new doors to answer questions that have been previously unanswerable either in the lab or in wild populations.