Advanced tokamaks seek to achieve a high bootstrap current fractionwithout sacrificing fusion power density or fusion gain. Good progress hasbeen made towards the DIII-D research goal of demonstrating a high-βadvanced tokamak plasma in steady state with a relaxed, fully non-inductivecurrent profile and a bootstrap current fraction greater than 50%. Thelimiting factors for transport, stability, and current profile control inadvanced operating modes are discussed in this paper.