(A) Generation of Kdm5a-/- constitutive knockout (KO) mice. Schematic of the targeted Kdm5a locus disrupting exon 13 resulting in a frameshift and loss of KDM5A. (B) Western blot analysis from cortical tissue lysates of WT, Kdm5a+/- (Het), or Kdm5a-/- (KO) mice showed a ~ 50% decrease in KDM5A protein level in the Het and complete loss of KDM5A in the KO mice compared to WT. Representative immunoblots from three independent experiments (n = 3 WT, 3 Het, 3 KO). (C) KO mice have severe reduction in the maximum peak frequency of ultrasonic vocalizations (USVs) and in the number of USVs measured at P4 (***p<0.0001; n = 22 WT, 49 Het, 9 KO). (D) KO mice spent 60% of the time wringing and clasping their forepaws compared to 5% for WT and 4% for Het littermates (***p<0.0001; n = 25 WT, 25 Het, 10 KO). (E) KO mice spent more time self-grooming compared to WT and Het littermates (*p=0.0107; n = 6 WT, 7 Het, 5 KO). During the duration of the analysis, WT and Het mice had ~1-2 grooming events, while KO mice had ~3-4 grooming events. (F) KO mice traveled a longer distance, and spent less time in the center and more time in the periphery of the open field compared to WT and Het littermates (total distance: **p=0.0014, time in center: **p=0.0015, time in periphery: *p=0.0143; n = 13 WT, 13 Het, 7 KO). (G) KO mice showed decreased social interaction with a novel partner mouse compared to WT and Het littermates (**p=0.0021; n = 11 WT, 8 Het, 6 KO). For (C), (D), (E), (F), and (G) data were analyzed using ordinary one-way ANOVA followed by Tukey's multiple comparisons test. (H) Compared to their control littermates, KO mice have an impaired learning shown by the latency to locate the hidden platform that does not decrease during the training phase of the Morris water maze task (day p<0.0001, genotype ***p<0.0001, day x genotype p=0.0012; n = 13 WT, 10 Het, 6 KO). Data were analyzed using two-way ANOVA followed by Tukey's multiple comparisons test. (I) KO mice performed poorly in the Morris water maze probe test compared to their control littermates and spent more time in non-target quadrants (Others) (WT: **p=0.0057, Het: **p=0.0034, KO: ***p<0.0001, target WT vs target KO: ***p=0.0004, target Het vs target KO: ***p<0.0001, target WT vs target Het: p=0.4433; n = 13 WT, 10 Het, 6 KO). Data were analyzed using unpaired t test for the within-genotype analyses and ordinary one-way ANOVA followed by Tukey's multiple comparisons test for the across-genotype analyses. All behaviors, except USV analysis, were assessed at 5–9 weeks of age. All values are mean ± SEM.