Frontotemporal dementia (FTD) is a neurodegenerative disease with hallmark deficits in social and emotional function. Heterozygous loss-of-function mutations inGRN, the progranulin gene, are a common genetic cause of the disorder, but the mechanisms by which progranulin haploinsufficiency causes neuronal dysfunction in FTD are unclear. Homozygous progranulin knock-out (Grn^−/−) mice have been studied as a model of this disorder and show behavioral deficits and a neuroinflammatory phenotype with robust microglial activation. However, homozygousGRNmutations causing complete progranulin deficiency were recently shown to cause a different neurological disorder, neuronal ceroid lipofuscinosis, suggesting that the total absence of progranulin may have effects distinct from those of haploinsufficiency. Here, we studied progranulin heterozygous (Grn^+/−) mice, which model progranulin haploinsufficiency. We found thatGrn^+/−mice developed age-dependent social and emotional deficits potentially relevant to FTD. However, unlikeGrn^−/−mice, behavioral deficits inGrn^+/−mice occurred in the absence of gliosis or increased expression of tumor necrosis factor-α. Instead, we found neuronal abnormalities in the amygdala, an area of selective vulnerability in FTD, inGrn^+/−mice. Our findings indicate that FTD-related deficits resulting from progranulin haploinsufficiency can develop in the absence of detectable gliosis and neuroinflammation, thereby dissociating microglial activation from functional deficits and suggesting an important effect of progranulin deficiency on neurons.