Background: Likert-type scales are increasingly being used among people with intellectual disability (ID). These scales offer an efficient method for capturing a wide range of variance in self-reported attitudes and behaviours. This review is an attempt to evaluate the reliability and validity of Likert-type scales in people with ID. Methods: Fifty-one studies reporting response rates, response bias, reliability and validity of Likert-type scales among adolescents and adults with ID were reviewed. Results: Low response rates were found among adolescents and adults with moderate to profound ID, when pictorial representations of response alternatives were not employed, and for Likert-type scales with self-descriptive statements. Response bias was evident, particularly among adolescents and adults with moderate to profound ID. Likert-type scales have better reliability and validity among adolescents and adults with borderline IQ or mild ID. Pretests and clarifying questions increase reliability and validity. Conclusions: Likert-type scales should include pictorial representations of response alternatives, a single set of one or two word response descriptors, clarifying questions, and pretests, and are best used with adolescents and adults with borderline IQ to mild ID.