The MTHFD1 gene encodes for methylenetetrahydrofolate dehydrogenase 1, an enzyme that has an important role in folate-mediated one-carbon metabolism. In people, a single nucleotide polymorphism of this gene (1958G > A; rs2236225) is associated with increased risk for bipolar disorder and schizophrenia, neural tube and other birth defects. Mice homozygous for a loss of Mthfd1 via a gene-trap mutation are not viable, and heterozygotes, though they appear healthy, have metabolic imbalances in the folate- and choline-mediated 1-carbon metabolic pathways. In this study, we evaluated cognitive function in Mthfd1gt/+ male and female mice using a behavioral battery composed of eight different tests. We found that these mice display impaired cue-conditioned learning, while other behaviors remain intact.