Facial attractiveness influences us in a variety of ways. Not only does it affect which partners we date, mate with or marry, but it also affects how we think about and interact with others. Nearly everyone has experienced how stunning attractiveness captures the eye. And nearly everyone enjoys looking at attractive faces. Moreover, advertisements of consumer products take advantage of the effects of facial attractiveness. The expectation here is that the positive effects of attractiveness would generalize to consumers’ product evaluations (Baker and Churchill, 1977). The preoccupation with attractiveness is also reflected in the considerable effort people put into looking attractive: “In the United States more money is spent on attractiveness than on education or social services” (Etcoff, 1999, p. 6). Thus, a multibillion-dollar industry lives off of the promise of increased attractiveness. It is, however, still unclear what the essence of facial attractiveness really is, but researchers have put considerable effort into revealing what, why and how different factors contribute to attractiveness. In the current chapter, we discuss what makes faces attractive and present some hypotheses on why this might be the case. We also show how our brains process attractiveness and how attractiveness affects various aspects of our experiences and behaviors. What is attractiveness? Throughout this chapter, we use the term “attractiveness” to refer to the aesthetic qualities of faces. Attractiveness is the most commonly used term in scientific studies. This common use of attractiveness is noteworthy because most people typically mention beauty, but not attractiveness, when discussing the aesthetic qualities of faces (Augustin, Wagemans and Carbon, 2012). However, there might be some difference between beauty and attractiveness. Beauty could refer more to aesthetic qualities of a face per se, while attractiveness could refer more to the function of aesthetic qualities of faces – indicating sexual and social qualities of potential mates (Little, Jones and DeBruine, 2011; Senior, 2003; Thornhill and Gangestad, 1999). Additionally, depending on the context, focusing on attractiveness might accentuate different aspects of aesthetic qualities of faces. In a mating context, for instance, sexual qualities might be considered more important for attractiveness evaluations, as compared to a non-mating context. Importantly, when evaluating a face, these aspects yield different motivational and emotional consequences. Thus, in our chapter, we will consider these aspects in the interpretation of results.