The World Builder's Handbook provides a complete toolset for expanding a world or star system into a fully realized place to know and explore. It includes procedures for determining the type and location of a system's significant stars and worlds, an expansion of mainworld generation, and rules for determining the physical and social characteristics of the star system's other worlds. This handbook is both comprehensive and modular, with procedures designed to allow the Referee to focus on the important aspects of a world or system's characteristics. The World Builder's Handbook includes knowledge gained from the thousands of exoplanetary systems discovered, and covers habitable and hostile worlds, moons, gas giants, twilight worlds and guidelines for the Referee to describe what Travellers can see in the skies above these worlds. It allows a Referee to create star systems from scratch or expand existing profiles to refine a world's character. Also included are checklists, forms, examples, and the procedures and equipment used by the Imperial Interstellar Scout Service to survey and record information in the Charted Space universe, with a glossary of astronomical terms.