Seamen's Protection Certificates were authorized by Congress in 1796 to identify American merchant seamen as citizens of the United States and, as such, entitled to protection against impressment at sea. This work is an index to the names of merchant seamen who made application for a Seamen's Protection Certificate (SPC) at the Port of Philadelphia between 1796 and 1823 and is a companion volume to the index to SPC applications filed between 1824 and 1861 which was compiled by Mrs. Dixon and published by Clearfield Company in 1994. The names of 14,397 seamen appear in this volume, and each is identified according to the date of the SPC application, age, race, and state or country of birth. Since seamen were unlikely to own land and often were missed at census time, the SPC application may be the only record available for many 18th-century persons who served in the American merchant marine.