High penetragtion of distributed energy resources (DER) in distribution systems not only introduces two-way power flows but also impacts system responses to various disturbances potentially threatening the reliability of Bulk Power System (BPS). Treating distribution systems as lumped loads is no longer sufficient to represent the impact of DER in the planning and operation of the BPS. At the same time, the advanced control capabilities of DER offer potential opportunities for improving BPS reliability when applied in a well thought-out manner. This panel will discuss the impact of high penetration DER on the BPS from various aspects, including BPS planning and operation, wholesale market participation by DER, BPS voltage, frequency, and dynamic stability. The DER modeling and interconnection standards, monitoring and control of DER will also be discussed, as well as details from the efforts of NERC's various working groups with respect to DER.