Parents play a critical role in the early identification of ASD because of their experiential knowledge and frequent observations of their children. Being knowledgeable about ASD may help parents recognize early signs and symptoms, know to which professionals to express their concerns, and better navigate systems of care. An appropriate measure of ASD knowledge for parents is essential to further understand the importance of ASD knowledge in this population. This study sought to validate the Autism Spectrum Knowledge Scale—General Population Version (ASKSG) with a sample of parents with children under the age of 18 years in the United States. Results indicate that the ASKSG is a valid and reliable measure for use with parents.