Mainly Young’s research working files and notes, together with his manuscripts of his writings, correspondence, and the works of historian colleagues. Most of this material focuses on Young’s research into the lives of everyday people, especially in Boston and New England. His correspondence with historians, graduate students, and others reveals his importance to many as a professional colleague and mentor.

Young’s research working files are boxed alphabetically by major topic as they were kept by Young. The research files also contain correspondence and writings of Young and his colleagues, also as they were kept by Young. Elizabeth Young, a daughter of Young, corresponded semi regularly with her father on historical matters. Folder titles placed in quotation marks signify titles of Young's that are considered harmful or outdated in today's culture. Where these titles cannot be changed, they have been included in their original form.