Data analysis and theoretical arguments support magnetic reconnection in a chromospheric current sheet as the mechanism of the observed photospheric magnetic ux cancellation on the Sun. Flux pile-up reconnection in a Sweet{Parker current sheet can explain the observed properties of canceling mag- netic features, including the speeds of canceling magnetic fragments, the magnetic uxes in the fragments, and the ux cancellation rates, inferred from the data. It is discussed how more realistic chromospheric reconnection models can be developed by relaxing the assumptions of a negligible current sheet curvature and a constant height of the reconnection site above the photosphere.