In this study, we evaluated the effect of the Future Center Early Intensive Behavioral Intervention program on children's skills longitudinally by sex, age, and diagnoses as dependent variables. Sixty-seven children ages 1-6 years and diagnosed with autism spectrum disorder were followed up for 2 years in Syria. They were assessed twice across the 2-year program: at their first visit and at the end of the program. Assessments included the Autism Behavior Checklist, Childhood Autism Rating Scale, and Adaptive Behavioral Scale--Arabic version. Results showed that the changes in participants' scores from pre- to post-test were statistically significant, and the treatment group showed significantly larger gains on all scales. No significant differences were found by sex and age between the pre- and post-test on all scales, while there were significant differences regarding diagnoses. The limitations of this study and suggestions for future research are described.