The objectives of this research study were to determine the effects of asphalt binder formulation and source on the performance of binders with the same continuous Performance Grade (PG) using recently developed asphalt binder and mixture tests and provide recommendations, if needed, concerning the following: (1) the effect of asphalt binder formulation and source on performance, (2) the current PG specification and (3) the tests used in this study. Various asphalt binders were formulated so they would have the same continuous high and low PGs which would meet the AASHTO M 320 specifications for a PG 58-28 binder. Other binders were formulated to meet the AASHTO M 320 specifications for a PG 64-28 binder. Thus, there were two target PG's. Three sources of straight run asphalt binders were obtained, although one source was eliminated because for most of the modifiers obtained for this study, the target PGs could not be met. This showed that whether a continuous PG can be achieved through modification is dependent on binder source and modifier type. The modifiers used in the formulations consisted of two sources of re-refined engine oil bottoms (REOB), aromatic oil, polyphosphoric acid (PPA) and an air-blown asphalt, either alone or in combination. It is believed these modifiers are becoming more commonly utilized to supply the required PG asphalt binders for today's paving industry. Asphalt binder formulation and source had an effect on fatigue cracking cohesion, adhestion, moisture susceptibilty and non-load associated cracking even though the binders had closely matching continuous PGs based on high and low temperature properties. They had no effect on rutting performance except when measured by the MSCR, or thermal cracking performance except when measured by the EBBR. In conclusion, not all asphalt binders with the same continuous PG will perform identically in regard to all distresses.