Abstract: A pet barrier includes a housing containing a barrier having a first end attached to a holding structure. The holding structure rotates with respect to the housing and the barrier is furled around the holding structure. The second end of the barrier is exposed from the housing and includes an elongated bar hook. The pet barrier also includes a tensioning mechanism including a spring assembly operably associated with the holding structure. An adjustment structure is provided for adjusting the tension of the spring assembly by rotational action and thereby adjusting tension in the barrier. To set the tension of the spring assembly, a brake is provided that locks the adjustment structure to with a portion of the housing and/or a portion fixed with respect to the housing. Constant retraction forces act upon the barrier as it is unfurled from around the holding structure.