PROJECT ABSTRACT Social attachments are a vital part of healthy human behavior and an inability to form such attachments is regarded as a symptom of mental disorders such as anti-social disorders, schizophrenia and autism. Studying the mechanisms underlying social attachment requires an animal model that displays behaviors similar to that of human social attachment. Prairie voles (Microtus ochrogaster) have become an important model for the study of the neurobiology of social attachment. In the field, male and female prairie voles form long-term, monogamous bonds and share a nest throughout the breeding season. Such a breeding pair typically remains together until one animal dies. Given that mating in prairie voles induces neuroadaptations that eventually lead to bonding, we propose here to investigate whether mating induced social bonding has an underlying epigenetic basis. Our preliminary data support this hypothesis.