The use of ground rubber from scrap tires has long been supported by environmental and government agencies to reduce the disposal problem associated with waste tires. In 2008, Louisiana turned to the use of crumb rubber in asphalt mixtures to address a shortage in polymer-modified asphalt binder. As a result, the state developed new specifications for rubberized asphalt binder, which allowed it as a substitute to polymermodified asphalt binder. This study presents the research activities that led to the development of the Louisiana rubberized specifications. A laboratory experimental program was conducted to evaluate the performance of asphalt mixtures prepared with crumb-rubber (CR) modified binder as compared to mixtures prepared with polymer-modified asphalt binder with and without Reclaimed Asphalt Pavement (RAP). In addition, the field performance of test sections constructed with CR modified binder was compared to a test section prepared with polymer-modified conventional mixtures under accelerated loading. Based on the results of the laboratory experimental program, it is concluded that the rutting and intermediate temperature fracture performances of CR modified asphalt mixture were adequate and comparable to mixtures prepared with polymer-modified asphalt binder. Test results from the accelerated loading facility (ALF) experiment showed acceptable performance for asphalt mixtures can be achieved using either polymer-modified or CR modified asphalt binders.