The evaluation begins with an extensive review of the individual's medical, developmental, and behavioral history. Clinicians examine medical records, previous evaluations, psychiatric hospitalizations, medication trials, and any prior therapeutic interventions. They look for patterns of behavioral difficulties that may stem from various conditions such as autism spectrum disorder, intellectual disability, attention-deficit/hyperactivity disorder (ADHD), disruptive behavior disorders, anxiety disorders, trauma-related disorders, or other neurodevelopmental conditions. The assessment also considers any medical conditions that might contribute to behavioral challenges, such as seizure disorders, genetic syndromes, or communication disorders.

Comprehensive interviews are conducted with parents, caregivers, teachers, and other relevant individuals who can provide detailed information about the person's behavioral patterns across different settings. These interviews focus on identifying specific problem behaviors, their frequency and intensity, triggers that precipitate challenging behaviors, and the impact these behaviors have on the individual's ability to function in home, school, and community environments. For individuals with communication abilities, self-reporting may be included to understand their perspective on their behavioral challenges.

The diagnostic process involves multiple standardized assessment tools depending on the suspected conditions. For autism spectrum disorder, tools like the CARS and ASRS are used. For other conditions, clinicians may use behavior rating scales, adaptive behavior scales, and mental health screening instruments.

Direct observation in natural environments is essential to document the severity and impact of behavioral challenges. Clinicians observe the individual across different settings to assess how behavioral symptoms interfere with learning, social relationships, family functioning, and community participation. They document specific behaviors such as aggression, self-injury, property destruction, severe tantrums, or other maladaptive behaviors that significantly impair the person's quality of life.

The final diagnostic report must clearly establish that the individual has a qualifying diagnosis that results in significant behavioral challenges requiring intensive behavioral intervention. Insurance companies require documentation that the behaviors are severe enough to warrant the intensity and cost of ABA therapy. The report must demonstrate medical necessity by showing that without ABA therapy, the individual's behavioral challenges will likely worsen or significantly impair their development, safety, or ability to function in typical environments. This comprehensive documentation ensures that individuals with various conditions causing severe behavioral challenges can access ABA therapy when it is clinically appropriate and medically necessary.