INTELLECTUAL disability or mentally challenged. Some key points about mental retardation:It is defined as well below level average level of intellectual functioning level and significant limitations in TWO or more adaptive skills.Adaptive skills are skills NEEDED for daily life such as communication and self-care.Measured by standard test for intelligence quotient such as Wechsler intelligence testMental retardation manifests before the age of 18. (HEWERD,2003)Mental retardation is defined as IQ below 70 to 75Mental retardation need not be a lifelong condition especially for those whose degree of retardation is very mild.IQ below 70 is considered as educable mentally retardedIQ 50-70 is termed as trainable mentally retardedIQ below 25 is termed as custodial mentally retarded.Hence, we can conclude that mental retardation manifests before the age of 18. Causes of Mental Retardation : Causes of mental retardation: M.R is a multidimensional problem of a combination of psycho-social, cultural, biological, and environmental factors. The chromosomal abnormalities causing VARIOUS types of mental defects notably Mongolism, have heightened interest in the field of etiology of mental deficiency.Injury or disease can trigger a process that leads to Mental disability. They place individuals in circumstances leading to impairment and functional limitations. In more severe cases of retardation, some sort of physical cause can be identified, such as BRAIN injury, disease, or accidents of development that produce normal intellectual growth. The mental impairment in these cases is usually related to brain damage and gross structural defects are often apparent in the nervous system.Mental retardation due to infections and intoxications by the mother during her pregnancy.Mental retardation due to Chronic infection and diseases in the post-natal period of pregnancy.Poor rural children with an inadequate diet show marked inferiority in physical and mental development compared to urban children. Lack of stimulation in the environment of poor children is another factor contributing to mental retardation.