The spectrum of SI1 from a sliding spark discharge has been recorded from 9650 A to 550 A. The wavelengths of 573 lines in the air region and 294 limes in the vacuum region were measured. Energy levels have been established or revised in the following confiurations: 3p4, 4s-7s, 4p-5p, 3d-7d, 4f-7f and 5g. Most of these configurations have been studied by means of ab initio calculations or least-squares fits. The ionization limit 3s23p2 'P, 189 066 c 2 cm-' was calculated from f and g levels.