Although individually rare, pathogenic genetic changes can now explain up to 40% of the cases of autism spectrum disorders (ASD) & intellectual disability (ID), which may have direct implications on clinical management. Multiple professional societies, including AACAP, recommend diagnostic molecular genetic testing as a routine part of the medical evaluation for people diagnosed with ASD or ID of undetermined etiology. Specifically, chromosomal microarray and Fragile X testing are considered as the standard of care, followed by whole exome sequencing in specific cases. There is, however, a large gap between professional recommendations & actual clinical practice, with a small minority of patients receiving these tests. Many factors contribute to this shortfall, including discomfort with ordering genetic testing, difficulties navigating the insurance authorization process, & lack of comfort in interpreting complex test results. And yet, some molecular genetic diagnoses may provide important context regarding genetic susceptibility to co-morbid conditions that could help guide treatment decisions. In this presentation, we will review key genetics concepts & highlight instances in which molecular genetic testing has shaped our clinical recommendations, along with steps to we are taking to move forward with research & clinical care in this area.