Most historical writing rests on earlier evidence. A secondary source is a work that interprets, analyzes, or synthesizes primary sources and other secondary works. Monographs, journal articles, and textbooks are typical examples.

Secondary sources organize facts into arguments, place events in context, and engage with existing scholarship. Their value depends on the quality of research, the transparency of reasoning, and the fairness with which evidence is handled. They are essential for learning the state of knowledge in a field.

Historians read secondary sources both for information and for historiographical position. A work that is secondary for one topic may serve as a primary source for the history of historical thought. Training includes evaluating secondary literature as critically as the primary evidence it discusses.

• Work interpreting primary sources and prior scholarship
• Includes books, articles, and surveys
• Organizes evidence into argument
• Evaluated for method and perspective