This study has found and compared the levels of autism knowledge and autism self-efficacy among general and special education teachers in Saudi Arabia. Furthermore, it has sought to determine potential relationships between autism knowledge and self-efficacy and teachers' gender, teaching experience, level of education, type of degree, and training. A total of 288 general and special education teachers in Jeddah, Saudi Arabia completed the study instruments, which included the Autism Knowledge Questionnaire, the Autism Self-Efficacy Scale for Teachers, and a demographics survey. The data analysis determined that teachers possessed a medium-to-low level of autism knowledge and a moderately high level of autism self-efficacy. In addition, a relationship was found between autism knowledge and self-efficacy; the more autism knowledge teachers possessed, the higher their self-efficacy. Higher autism knowledge was correlated with having a special education degree, having achieved a higher degree, and either being a new teacher or having many years of experience. Having autism training was the only variable correlated with having both higher autism self-efficacy and knowledge.