A spectroscopic study of the bright spiral galaxy NGC 253 has been carried out at McDonald Observatory A rotation-curve extending out to 290" from the center, or just less than half the radius of the visible distribution of matter, has been derived; the mass interior to 290" is about 5 X 1010 M0. The Keplerian mass estimate from the velocity of an emission knot at 400" (8000 pc) from the center is 2.0 X 1011 M0. If we assume that the rotation velocity remained at that value out to the edge of the visible matter (whereas it is likely to drop), we obtain an upper limit for the mass of 3 2 X 1011 M0. The mass-to-light ratio (photographic) is <9. Spectra taken at various position angles indicate the occurrence of non- circular motions in the nuclear region. Irregular dust structures throughout the galaxy, together with irregularities of +30 km/sec in the rotation-curve, suggest the occurrence of irregular motions on a scale 500 pc; small-scale random motions are also indicated in the nucleus.