As the penetrations of renewable energy resources deepen in electric power grids around the world, their impacts on the grid’s resource adequacy become more significant. The marked intermittent and time-varying nature of renewable resources (RRs) cannot be appropriately represented in the widely-used time-invariant resource adequacy evaluation approach. In this presentation we discuss the development of a resource adequacy evaluation framework with the capability to represent the uncertain and time-varying nature of demand and supply resources, including those of renewable technologies. The framework uses Monte Carlo simulation as the primary tool for the evaluation of the resource adequacy metrics as well as the sensitivity measures introduced to quantify the impacts of deepening RR penetrations on these metrics. We present representative results from our extensive application studies to the New York state control area. The study results presented effectively illustrate the challenges faced by the electric power industry in the resource adequacy area.