From the beginning of the Institution until around 1880, almost all business was conducted through the Secretary's office. Accordingly, information on the early history of the Smithsonian is often found in these records. There are almost no Secretary's records from 1846-1863 since a fire in 1865 in the Smithsonian Institution Building, the Castle, destroyed the early files. Secretary's records (as was the case with all correspondence files at the Smithsonian) were maintained in separate incoming and outgoing series until 1907. Outgoing correspondence was maintained in letterpress copy books. After 1907, the modern filing system was adopted and incoming letters and their responses were filed together.
The Smithsonian Archives also holds the personal papers of the Secretaries. The distinction between "official" and "personal" is often quite blurred—especially in the 19th century. So, if a particular item is not found in the official files (Secretary's records), it is a good idea to consult the personal papers—and vice versa.
Secretaries have included:
- Joseph Henry, 1846–1878
- Spencer F. Baird, 1878–1887
- Samuel P. Langley, 1887–1906
- Charles D. Walcott, 1907–1927
- Charles G. Abbot, 1928–1944
- Alexander Wetmore, 1944–1952
- Leonard Carmichael, 1953–1964
- S. Dillon Ripley, 1964-–1984
- Robert McCormick Adams, 1984–1994
- Ira Michael Heyman, 1994–2000
- Lawrence M. Small, 2000–2007
- G. Wayne Clough, 2008–2014
- Dr. David Skorton, 2015-present