Children diagnosed with Autism Spectrum Disorders (ASD) face a variety of challenges such as the inability to communicate verbally. The Picture Exchange Communication System is an early intervention program that has shown to increase the verbal communication skills of some children with ASD. However, how PECS increases verbal communication in some children with ASD is unknown. To understand how PECS leads to verbal communication in some children with ASD, researchers must use a consistent set of reliable measures with specific groups of children with ASD. This literature review analyzed the three most frequently used standardized measurement tools used to assess children with ASD in PECS research; Vineland Adaptive Behavior Scales (VABS), Autism Diagnostic Observation Schedule (ADOS), and the Childhood Autism Rating Scale (CARS). VABS is a measure which can determine intellectual disability. VABS should be used with children that begin PECS without any verbal skills. ADOS is a measure used to support an ASD diagnosis. ADOS should be used with all children that are placed in the PECS program, with low functioning to high functioning ASD. CARS can retrospectively measure the abilities of a child with ASD. CARS should be used with children with ASD that begin using PECS at a later age.