What does behavioral variation among individuals and behavioral plasticity look like at the molecular level? In this talk I will present two cases studies illustrating some of the complexities, nuances, and opportunities for studying variation and plasticity in behavior at the molecular level in threespined sticklebacks, a species famous for its behavioral repertoire and evolution. The first study uses a time-series approach to investigate behavioral plasticity at the molecular level in the brain in response to a brief territorial challenge. Following a social challenge, there were multiple waves of transcription associated with distinct molecular functions in the brain. We identify transcription factors that are predicted to coordinate waves of transcription and show that a brief social interaction was sufficient to cause rapid and dramatic changes in chromatin accessibility. We integrate the time course brain gene expression data with a transcriptional regulatory network, and link changes in gene expression to changes in chromatin accessibility and transcription factor binding. This study reveals rapid and dramatic epigenomic plasticity in response to a brief, highly consequential social interaction. The second study investigates the inheritance, plasticity and neurogenomics of parental care. We found that individual variation in parental care was highly heritable: fathers that provided high levels of paternal care produced offspring that also exhibited high levels of paternal care. Parental care is highly plastic in response to cues of predation risk, regardless of whether risk is experienced personally, by their mate, or by their father. Finally, the process of becoming a father is associated with dramatic changes in brain gene expression and chromatin accessibility. Altogether these findings illustrate the need for new tools, concepts and approaches that allow us to integrate quantitive genetics with neurogenomic and epigenomic data to understand variation and plasticity in behavior.