The date range for this collection spans from 1904 to 1993. Highlights include a series of letters from Pascal Covici — Steinbeck’s longtime friend and editor — to the author, commenting on their relationship. The Correspondence Collection at the National Steinbeck Center consists of three series of letters.

• Series I: To or from John Steinbeck
• Series II: To or from a family member of John Steinbeck
• Series III: To or from a friend or acquaintance of John Steinbeck