Many animals are relinquished to shelters for behavioral issues; thus, it is important that behavior is addressed so future matches between pets and adopters have the best chance for success. With the support of American Humane, the student attempted to determine the best time for assessing behavior in shelter dogs. Thirty-three dogs received an ASPCA SAFER® Aggression Assessment on shelter intake and again following a 3-day acclimation period. Fifty individual tests showed a change in the level of aggression at the 3-day evaluation. Thirty-one test results showed a lower score (lower demonstration of aggression), while 26 test results yielded the opposite result. Additionally, one month after adoption, owners of dogs that had been enrolled in the study were contacted and asked to complete a validated questionnaire, so that the dog’s behavior in a home setting could be compared with SAFER® test results obtained in the shelter. Analyses of these data are ongoing. Knowing when to assess can enable shelters to manage their resources more efficiently and effectively, and is essential to protect shelter staff and adoptive families.