The power grids across the world are evolving on a path different than traditional generation and transmission expansion. Driven by economic and environmental factors, consumer engagement and participation fundamentally move the grid onto a path that all parts of the grid become active. The power system exhibits significant interactions between transmission and distribution system with greater dependency on a variety of communication media. This leads to a revolution in how the power system should be planned and operated. Such revolution requires modeling and simulation capabilities to understand the interdependency of transmission, distribution and communication (TDC) systems and build confidence in deploying systems that will meet, or improve upon, current reliability, security, efficiency and cost-effective benchmarks. This half-day tutorial will provide participants a solid understanding of TDC interactions, the need for TDC integrated modeling and possible solution methods with demonstrative examples. The cross-domain nature of this topic calls for technical leadership by the IEEE PES to bring diverse sets of experts together to further advance such integrated modeling capabilities.