The Trace Amines-Associated Receptor 1 (TAAR1) is one of the six functional receptors belonging to the family of monoamine-related G protein-coupled receptors (TAAR1-9) in humans. However, the exact biological mechanisms of TAAR1 central and peripheral action remain poorly understood. For example, TAAR1 is widely expressed in the prefrontal cortex and several limbic regions, and interplays with the dopaminergic systems to modulate the limbic functions and the reward circuitry. Recent clinical trials suggest TAAR1 agonists as potential novel antipsychotic agents. Here, we characterize the behavioral phenotype of TAAR1 knockout mice (TAAR1-KO), focusing on aggression, monoaminergic signaling, and corticostriatal and corticolimbic circuits.