During the past century, β-lactams have been identified as the core of penicillin and since then several strategies have been developed for their synthesis. Traditional methods for β-lactam synthesis usually involved amide bond formation and the Staudinger reaction. In recent years, by the advancement of photo- and transition metal-catalysis, several new methods have been reported for β-lactam synthesis. For instance: ligand assisted metal catalyzed C-H activation/intermolecular oxidative amidation draws attention for β-lactam synthesis. In this review we introduce methods for β-lactam synthesis and present newly developed reactions. We approach the synthesis of β-lactams according to different retro synthesis strategies.