We investigated the effect of a live online educational program in 93 Dutch Youth and Family Center (YFC) physicians who were screening for Autism Spectrum Disorder (ASD) in the general child population. The educational program raised the physicians’ level of specific ASD knowledge and it remained higher at six months follow-up (p < .01). Their self-confidence in detecting ASD was also higher and maintained at follow-up (p < .01). The educational program had no effect on the physicians’ stigmatizing attitudes toward mental illness nor on the number of potential ASD referrals in children of 4–6 years of age. In conclusion, the online educational program on early detection of ASD has a six month long effect on YFC physicians’ level of ASD knowledge and self-confidence.