The choice to use electricity markets to transition to an ultra-high renewable electricity sector depends on whether a high level of reliability and efficiency can be achieved. This study presents a reliability, resiliency and adaptability policy framework for a liberalized power system with a high share of renewables. This framework provides policy insights regarding electricity market reliability and the implications of remuneration mechanisms for renewables. Our analysis shows that it is necessary to reconsider adequacy assessments of liberalized power systems, to enhance the definition of the loss of load probability, and to explicitly consider the probability that the market clears. Under these conditions, electricity markets can theoretically achieve reliability and efficiency with large percentages of variable and intermittent renewable resources with zero or near-zero marginal costs, and market and technical challenges can be addressed.