Traditional Levels of Mental Retardation Based on IQ

Mild Mental Retardation - IQ score in the range of 50-55 to 70


Moderate Mental Retardation - IQ score in the range of 35-40 to 50-55


Severe Mental Retardation - IQ score in the range of 20-25 to 35-40

Profound Mental Retardation – IQ score below 20-25

Reference: Hourcade, J. (2002). “Mental Retardation: Update 2002.” ERIC EC Digest #E637. Available at http://www.hoagiesgifted.org/eric/e637.html