A directional wavemaker theory is presented for waves in wave basins with sloping bottoms and reflective sidewalls. The theory includes the refraction, shoaling and diffraction that occur in wave basins with the wavemaker mounted along one end of the basin. A procedure is shown which utilizes the reflection from the sidewalls to produce planar wave trains at a given location in the basin, similar to that which would be obtained by an infinitely long wavemaker.