A narrowband (5 GHz) electron beam pumped XeF oscillator/amplifier, lasing at 353.2 nm over a 1‐&mgr;s pulse duration, has been demonstrated. Line selection, bandwidth narrowing, and near‐diffraction‐limited output are achieved by using an echelle grating and an intracavity solid e´talon in a stable oscillator configuration. The amplifier features an off‐axis design and yields output energies ≳0.8 J. The oscillator and amplifier are located in the same gas chamber and are transversely pumped by the same electron beam. A Fabry–Perot interferometer together with a streak camera is used to verify narrowband operation over the entire pulse duration.