This tutorial will inform attendees of emerging challenges and opportunities in transmission planning and introduce them to methods to address these challenges and take advantage of these opportunities throughout the transmission planning process, with a focus on the execution of quantitative studies. The following challenges and opportunities will be addressed: (a) Extreme weather and natural disasters (challenge). (b) Large-scale loads and other phenomena on the load side (challenge). (c) Decarbonization policies (challenge). (d) New technologies (FACTS, GETs, etc.) (opportunity). First, each of the challenges and opportunities will be addressed separately, covering: (1) Description of the challenge or opportunity. (2) Incorporation into the transmission planning process: (2.1) Modeling and decision-making in quantitative studies. (2.2) Stakeholder consultation and other process requirements. The trainers will then explore how to consider interactions between these challenges and opportunities to ensure transmission planning contributes to supply reliability, affordability, and sustainability.