The apostle Paul's first letter to the church in Thessalonica.

1 Thessalonians is sometimes held to be the first of Paul's surviving epistles (Galatians being the principal contender). On the most common chronology, it was written while he was in Corinth with Timothy & Silas (the co-authors) on his 2nd missionary journey, circa AD 50, having passed through and spent time in Thessalonica several months prior.

Paul indicates he had worried that the Thessalonians had faltered in their faith, and he is writing to them after Timothy had traveled to Thessalonica and returned.