This research addresses the challenges of assessing receptive language abilities in minimally verbal children with autism spectrum disorder by comparing several adapted measurement tools: a standardized direct assessment of receptive vocabulary (i.e. Peabody Picture Vocabulary Test-4); caregiver report measures including scores on the Vineland-II Communication domain and a vocabulary questionnaire consisting of a list of words ranging from simple, developmentally early, to more advanced words expected to be understood by at least some older children and adolescents; an eye-tracking test of word comprehension, using a word-image pair matching paradigm similar to that often used in studies of infant language acquisition; and a computerized assessment using a touch screen for directly measuring word comprehension with the same stimuli used in the eye-tracking experiment. Results of this multiple-method approach revealed significant heterogeneity in receptive language abilities across participants and across assessment methods. Our findings underscore the need to find individualized approaches for capturing the potential for language comprehension of minimally verbal children with autism spectrum disorder who remain otherwise untestable, using several types of assessment that may include methods based on eye-tracking or touch-screen responding.