Dog shelters provide a valuable service by housing homeless dogs and seeking subsequent adoption for these dogs. Few studies have aimed to monitor the behavior of adopted dogs when adoption is successful. The aim of this study was to detect what behavioral modifications, based on their personality, occurred in dogs after their adoption. The personality of 34 healthy dogs was evaluated in the pre-adoption phase by means of a Principal Component Analysis (PCA) of their behavioral patterns. In the post-adoption phase, we analyzed the behavior of the same dogs, completing a questionnaire with their owners. Pre- and post-adoption data were standardized and a PCA was run on the differences between these variables. A k-means cluster analysis was run on the six components, obtaining three groups of dogs: for groups one and two, changes in behavior after adoption seemed to be influenced by dog personality: bolder dogs (1st group) became more active, excitable and playful, showed increased aggressive behavior towards humans, and decreased anxious and submissive behavior towards dogs and humans; shyer dogs (2nd group) went in the opposite direction, displaying increased aggressive behavior. For the 3rd group, personality was not predictive of behavior changes. All the dog adoptions in this study were successful.