James H. Marsh grew up in the rough Toronto neighbourhood of the Junction, surviving a difficult childhood. He began his career in publishing at a summer job with Holt, Rinehart and Winston learning the business from copy editing to typesetting and printing. At HRW, he was the editor of a centennial history of Canada called Canada: Unity and Diversity, later becoming the editor of the Carleton Library Series. His love of the book business led him into a prized job at The Canadian Encyclopedia, where he was editor in chief.