Germline heterozygous mutations in Pten (phosphatase and tensin homolog) are associated with macrocephaly and autism spectrum disorders (ASD). Pten germline heterozygous (Pten+/−) mice approximate these mutations, and both sexes show widespread brain overgrowth and impaired social behavior. Strikingly similar behavior phenotypes have been reported in oxytocin (Oxt) and/or oxytocin receptor (OxtR) knockout mice. Thus, we hypothesized that the behavioral phenotypes of germline Pten+/− mice may be caused by reduced Pten function in Oxt‐expressing cells. To investigate this, we tested mice in which Pten was conditionally deleted using oxytocin‐Cre (Oxt‐Cre+; PtenloxP/+, Oxt‐Cre+; PtenloxP/loxP) on a battery including assays of social, repetitive, depression‐like, and anxiety‐like behaviors. Minimal behavioral abnormalities were found; decreased anxiety‐like behavior in the open field test in Oxt‐Cre+; PtenloxP/loxP males was the only result that phenocopied germline Pten+/− mice. However, Oxt cell size was dramatically increased in Oxt‐Cre+; PtenloxP/loxP mice in adulthood. Thus, conditional deletion of Pten using Oxt‐Cre has a profound effect on Oxt cell structure, but not on ASD‐relevant behavior. We interpret these results as inconsistent with our starting hypothesis that reduced Pten function in Oxt‐expressing cells causes the behavioral deficits observed in germline Pten+/− mice. Autism Res 2016, 9: 1248–1262. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.