Historically, distribution systems have been designed with the objective of supplying customer loads, with electric power flowing in a single direction, from substations through radial primary and secondary lines to end users. The interconnection of Distributed Energy Resources (DER) violates this fundamental assumption and therefore, can lead to a wide variety of impacts that need to be assessed and mitigated. For instance, the variable output characteristic of the most popular renewable distributed generation (DG) technologies, such as solar photovoltaic (PV) and wind, can lead to bidirectional power flows, from substations to end users and vice versa, voltage fluctuations and interaction with voltage regulation and control equipment. Moreover, for large penetration levels of variable DG, distribution feeders can essentially become active sources and inject power beyond distribution substations, into subtransmission and transmission systems. This webinar will discuss modeling and simulation methodologies to evaluate impacts and solutions for seamless integration of DER, and discuss industry trends and leading practices in this area.