The current study reviewed all prior studies conducted on family home movies of infants who would be later diagnosed with autism spectrum disorder (ASD). Out of 41 original reports found since 1975, we retained 18 studies (317 films, maximum), sorted according to their methodological design using a quality grid. In the first 2 years of life, signs that differentiated children with ASD from children with developmental delays were as follows: less of a response to their name, less looking at others, lower eye contact quality and quantity, less positive facial expression and intersubjective behaviors (e.g., showing shared attention). Studies focusing on regression confirmed the clinical validity of the phenomena. We conclude that findings from home movies studies along with prospective studies have created the bases for identification of infants and toddlers at risk of developing ASD before the 18-24-month period, despite early diagnosis of autism remains a complex challenge. (Contains 3 tables and 1 figure.)