Regulator of G protein signaling 14 (RGS14) is a multifunctional signaling protein that suppresses synaptic plasticity in the mouse brain. Our previous studies showed that RGS14 is highly expressed in postsynaptic dendrites and spines of pyramidal neurons in hippocampal area CA2 of the developing mouse brain. However, our more recent work with adult rhesus macaque brain shows that RGS14 is found in multiple neuron populations throughout hippocampal areas CA1 and CA2, caudate nucleus, putamen, globus pallidus, substantia nigra, and amygdala in the adult rhesus monkey brain. In the mouse brain, we also have observed RGS14 protein in discrete limbic regions linked to reward behavior and addiction, including the central amygdala and nucleus accumbens, but a comprehensive mapping of RGS14 protein expression in the adult mouse brain is lacking. Here, we report that RGS14 is more broadly expressed in mouse brain than previously known. Intense RGS14 staining is observed in specific neuron populations of the hippocampal formation, amygdala, septum, bed nucleus of the stria terminalis, and nucleus accumbens. RGS14 is also observed in axon fiber tracts including the dorsal fornix, fimbria, stria terminalis, and the ventrohippocampal commissure. Moderate RGS14 staining is observed in various other adjacent regions not previously reported. These findings show that RGS14 is expressed in brain regions that govern aspects of core cognitive functions including sensory perception, emotion, memory, motivation, and execution of actions, and suggests that RGS14 may serve to suppress plasticity and filter inputs in these brain regions to set the overall tone on experience-to-action processes.