Background: The study reported here was an examination of the reliability of a method for determining acquiescent responding and the capacity to respond to items using a Likert scale response format by adults with an intellectual disability. Method: Reliability of the outcomes of these procedures was investigated using a test-retest design. Associations with receptive vocabulary were examined. Results: The majority of the participants did not demonstrate acquiescent responding. Individuals' responses to the Likert-type discrimination tasks were consistent, although this varied somewhat depending upon the abstractness of the task. There was some association between receptive language age equivalence scores and respondent performance. Conclusion: It is recommended that the pretest protocol (a) be modified to improve its reliability, and (b) this modified version be used with study participants who have an intellectual disability to ascertain the appropriate level of choice to be used for items that use a Likert response format.