Relationships with family are important to our emotional health and can play a significant role in our social success. We need our families and yet frequently have a great difficulty understanding them. Hundreds of books have been published with the goal of improving understanding and relationships among family and relationships; few, if any, have done so with an evolutionary approach. The Oxford Handbook of Evolutionary Family Psychology focuses on the reasons underlying family behavior and how a greater understanding of these factors can help us to better understand our own family behaviors. Recognizing that a deeper understanding of human families can be found through an understanding of similar phenomena in other species, the volume demonstrates how an understanding of family ties can inform understanding of our relationships to non-kin.