Accurate measures of changes in workplace attitudes toward people with disabilities are required to determine whether employee training and other interventions are effective. This critical systematic review searched Medline, PsycInfo, Google Scholar, Cinahl, and Cochrane Collaboration for suitable instruments published between 2005 and 2015, and for those published earlier if still indicated to be in active use. In total, 13 scans were conducted. Inclusion criteria included wildcard and free text variations of workplace attitudes, adults with disabilities, and competitive employment. In total, 9 of 49 studies were selected for review. Data from each of these were categorized through the PICO model (Population, Intervention, Comparison, and Outcome), mapped within a PRISMA flow chart, and analyzed through an 18-point weight of evidence framework for empirical quality, relevance, and evidence of theoretical validity. Weight of evidence scores for empirical quality ranged from 10 to 16 out of a possible score of 18. None of the studies provided an explicit evidence of theoretical validity. Measures of responsiveness to change in workplace attitudes appear less well validated than those for single timeframes.