Abstract Peace is arguably the problem of the 21st century. Peacefulness is not uniquely human, but a dearth of it among humans disproportionately threatens people and other animals around the globe. The urgent need for peace—if not immediately, everywhere, at any cost, then soon, as a pervasive norm—coincides with unprecedented scholarly attention to peace and to the implications of evolution for psychological functioning in the context of complex sociality. The time is ripe to integrate evolutionary perspectives into peace studies. Toward that end, this chapter describes potential impediments to an evolutionary peace project, provides a basic lexical and conceptual tool kit, and identifies some promising research directions.