Content validity and reliability of the Brief Assessment of Motor Function (BAMF) Upper Extremity Gross Motor Scale (UEGMS) were evaluated in this prospective, descriptive study. The UEGMS is one of five BAMF ordinal scales designed for quick documentation of gross, fine, and oral motor skill levels. Designed to be independent of age and diagnosis, it is intended for use for infants through young adults. An expert panel of 17 physical therapists and 13 occupational therapists refined the content by responding to a standard questionnaire comprised of questions, which asked whether each item should be included, is clearly worded, should be reordered higher or lower, is functionally relevant, and is easily discriminated. Ratings of content validity exceeded the criterion except for two items, which may represent different perspectives of physical and occupational therapists. The UEGMS was modified using the quantitative and qualitative feedback from the questionnaires. For reliability, five raters scored videotaped motor performances of 10 children. Coefficients for inter-rater (0.94) and intra-rater (0.95) reliability were high. The results provide evidence of content validity and reliability of the UEGMS for the assessment of UEGM skill. (Contains 3 tables.)