Humans' everyday experience of the world is influenced by our mood . Moods are consciously accessible affective states that extend over time that are characterized by their valence and arousal . They also likely have a long evolutionary heritage and serve as an important adaptive affective mechanism . When they become maladaptive or overly biased, pathological affective states such as depression can emerge . Despite the importance of moods for human experience, little is known about their causal neurobiological mechanisms . In humans, methodological and interpretational limitations prevent causal investigations into the origins of mood, highlighting the importance of animal models . Nonhuman primates that share key neuroanatomical, affective, and social features with humans will be essential to uncovering their foundation . Identifying and validating mood-like states in animals is, however, challenging not least because mood is a human construct requiring verbal communication . Here we outline a theoretical framework for animal models of human mood, drawing upon established psychological literature where it exists before reviewing the extant studies of non-human primate models of mood-like states.