What are the four levels of IDD?

People with intellectual developmental disorders (IDD) experience limitations in both intellectual functioning and adaptive behaviors (such as social skills or daily living skills). 

Although IDD has clear diagnostic criteria, it can look very different from one person to another. To help describe the range of support needs, intellectual disabilities are grouped into four levels: mild, moderate, severe, and profound.

The four levels of IDD are: 

• Mild Intellectual Disability – Individuals can master elementary-school level reading, writing, and math. They can usually live fairly independently, but may need help with more complex tasks, like managing money or planning ahead.
• Moderate Intellectual Disability – Individuals can learn basic reading and math with support. They need regular help with daily activities.
• Severe Intellectual Disability – Individuals can understand simple communication and use short phrases or gestures to express themselves. They typically need consistent caregiver support.
• Profound Intellectual Disability – Individuals primarily communicate through nonverbal methods, like facial expressions or gestures, and usually require full-time care and support.

Most people with intellectual disability will need some form of support throughout their lives. However, it’s important to remember that about 85% of individuals with IDD fall within the “mild” category, and with the right support, many can live relatively independent, happy lives. 

Learn more about each of the four levels of IDD here.