What kind of phenomenon is romantic love? Many philosophers, psychologists, and ordinary folk think it is an emotion. I challenge this assumption and argue instead that romantic love is best characterized as a syndrome ⎼ a pattern comprised of different kinds of mental states and behaviors that tend to co-occur. An examination of major emotion theories in philosophy and psychology demonstrates that romantic love does not fit into any of them. Likewise, the commonly endorsed but increasingly controversial categories of basic and nonbasic emotions do not account for romantic love. While both culture and evolution have shaped the phenomenon of romantic love, the dominant evolutionary story about romantic love does not stand up to scrutiny; nei...